identity: clarify blob format for v3/credentials

The current request/response examples show the credential blob as
a dict for type==ec2, which in incorrect, keystone expects it to
be a json serialized dict, also the description is incorrect, saying
"access_key" when it should be just "access".

These examples align the API docs with what the code actually does,
and also with these docs which say the blob is JSON serialized:
https://github.com/openstack/identity-api/blob/master/\
openstack-identity-api/v3/src/markdown/\
identity-api-v3.md#create-credential-post-credentials

Change-Id: Ieb7b7168f6c041b67a4f43742cb6a540971ff80e
Related-Bug: #1269637

api-ref/src/wadls/identity-api/src/v3/samples/CredentialCreateRequest.json

@@ -1,9 +1,7 @@
 {
-    "blob": {
-        "access": "...",
-        "secret": "..."
-    },
+    "blob": '{"access": "--access-key--",
+              "secret": "--secret-key--"}',
     "project_id": "--project-id--",
     "type": "ec2",
     "user_id": "--user--id--"
-}
+}

api-ref/src/wadls/identity-api/src/v3/samples/CredentialCreateResponse.json

@@ -1,8 +1,6 @@
 {
-    "blob": {
-        "access": "...",
-        "secret": "..."
-    },
+    "blob": '{"access": "--access-key--",
+              "secret": "--secret-key--"}',
     "id": "--credential-id--",
     "links": {
         "self": "http://identity:35357/v3/credentials/--credential-id--"
@@ -10,4 +8,4 @@
     "project_id": "--project-id--",
     "type": "ec2",
     "user_id": "--user--id--"
-}
+}

api-ref/src/wadls/identity-api/src/v3/samples/CredentialGetResponse.json

@@ -1,8 +1,6 @@
 {
-    "blob": {
-        "access": "...",
-        "secret": "..."
-    },
+    "blob": '{"access": "--access-key--",
+              "secret": "--secret-key--"}',
     "id": "--credential-id--",
     "links": {
         "self": "http://identity:35357/v3/credentials/--credential-id--"
@@ -10,4 +8,4 @@
     "project_id": "--project-id--",
     "type": "ec2",
     "user_id": "--user--id--"
-}
+}

api-ref/src/wadls/identity-api/src/v3/samples/CredentialUpdateResponse.json

@@ -1,8 +1,6 @@
 {
-    "blob": {
-        "access": "...",
-        "secret": "..."
-    },
+    "blob": '{"access": "--access-key--",
+              "secret": "--secret-key--"}',
     "id": "--credential-id--",
     "links": {
         "self": "http://identity:35357/v3/credentials/--credential-id--"
@@ -10,4 +8,4 @@
     "project_id": "--project-id--",
     "type": "ec2",
     "user_id": "--user--id--"
-}
+}

api-ref/src/wadls/identity-api/src/v3/samples/CredentialsListResponse.json

@@ -1,9 +1,8 @@
 [
     {
-        "blob": {
-            "access": "...",
-            "secret": "..."
-        },
+        "blob": '{"access": "--access-key--",
+                  "secret": "--secret-key--"}',
+
         "id": "--credential-id--",
         "links": {
             "self": "http://identity:35357/v3/credentials/--credential-id--"
@@ -13,10 +12,8 @@
         "user_id": "--user--id--"
     },
     {
-        "blob": {
-            "access": "...",
-            "secret": "..."
-        },
+        "blob": '{"access": "--access-key--",
+                  "secret": "--secret-key--"}',
         "id": "--credential-id--",
         "links": {
             "self": "http://identity:35357/v3/credentials/--credential-id--"
@@ -25,4 +22,4 @@
         "type": "ec2",
         "user_id": "--user--id--"
     }
-]
+]

api-ref/src/wadls/identity-api/src/v3/wadl/identity-admin.wadl

@@ -1643,11 +1643,13 @@
         <wadl:doc xml:lang="EN" xmlns="http://docbook.org/ns/docbook"
             title="Add Credential">
             <para role="shortdesc">Adds a credential.</para>
-            <para>The following example shows creating an EC2 style
-                credential where the credentials are a combination of
-                access_key and secret. Other credentials, such as
-                access_key, can be supported simply by changing the
-                content of the key data.</para>
+            <para>The following example shows how to create an EC2-style
+                  credential where the credential blob is a JSON-serialized
+                  dictionary that contains <code>access</code> and 
+                  <code>secret</code>. This format is required when you specify
+                  the <code>ec2</code> type. To specify other credentials, such
+                  as <code>access_key</code>, simply change the type and
+                  contents of the data blob.</para>
         </wadl:doc>
         <request>
             <representation mediaType="application/json">