Remove references to '24 hour' tokens

The token lifespan used by a deployment is configurable via
`keystone.conf [token] expiration` - it may not be 24 hours.

In fact, bp reduce-default-token-duration recently reduced the default
token duration from 24 hours to just one hour. The keystone community
expects to tweak this value over the next several releases, so I've
avoided using a specific value here to reduce maintenance effort.

https://blueprints.launchpad.net/keystone/+spec/reduce-default-token-duration

Change-Id: I86afd624c2d8ef4de3275ebaf3ceab80ef324f3e

api-quick-start/src/docbkx/api-quick-start-intro.xml

@@ -4,22 +4,24 @@
     xmlns:xlink="http://www.w3.org/1999/xlink"
     xml:id="Compute_API_Quick_Start" version="5.0">
     <title>OpenStack APIs</title>
-    <para>To authenticate access to OpenStack services, you issue an
-        authentication request to the OpenStack Identity Service. You
-        must supply a payload of credentials in the authentication
-        request.</para>
+    <para>To authenticate access to OpenStack services, you must first
+        issue an authentication request to the OpenStack Identity
+        Service to acquire an authentication token. To request an
+        authentication token, you must supply a payload of credentials
+        in the authentication request.</para>
     <para>Credentials are usually a combination of your user name and
         password, and optionally, the name or ID of the tenant in
         which your cloud runs. Ask your cloud administrator for your
         user name, password, and tenant so that you can generate
         authentication tokens. Alternatively, you can supply a token
         rather than a user name and password.</para>
-    <para>A token is typically valid for 24 hours. When you send API
-        requests, you include the token in the
-            <literal>X-Auth-Token</literal> header. You must generate
-        another token if you interact with your cloud through API
-        endpoints rather than through a client.</para>
-
+    <para>When you send API requests, you include the token in the
+            <literal>X-Auth-Token</literal> header. If you access
+        multiple OpenStack services, you must get a token for each
+        service. A token is valid for a limited time before it
+        expires. A token can also become invalid for other reasons.
+        For example, if the roles for a user change, existing tokens
+        for that user are invalid.</para>
     <orderedlist>
         <title>Authentication and API request workflow</title>
         <listitem>
@@ -92,7 +94,8 @@
                     <literal>X-Auth-Token</literal> header. Continue
                 to send API requests with that token until the job
                 completes or a <errorcode>401</errorcode>
-                <errortext>Unauthorized</errortext> error occurs.</para>
+                <errortext>Unauthorized</errortext> error
+                occurs.</para>
         </listitem>
         <listitem>
             <para>If the <errorcode>401</errorcode>

api-ref/src/docbkx/ch_identity-admin-v2.xml

@@ -9,7 +9,7 @@
     xlink:href="#identity-admin-v2">
     <title>Identity Service admin API v2.0</title>
     <para>Gets an authentication token that permits access to the
-        Compute API for 24 hours.</para>
+        Compute API.</para>
     <wadl:resources
         href="../wadls/identity-api/src/v2.0/wadl/identity-admin.wadl"
         xmlns:wadl="http://wadl.dev.java.net/2009/02">

api-ref/src/docbkx/ch_identity-v2.xml

@@ -22,7 +22,7 @@
     xlink:href="#identity-v2">
     <title>Identity Service API v2.0</title>
     <para>Gets an authentication token that permits access to the
-        Compute API for 24 hours.</para>
+        Compute API.</para>
     <wadl:resources
         href="../wadls/identity-api/src/v2.0/wadl/identity.wadl"
         xmlns:wadl="http://wadl.dev.java.net/2009/02"/>

api-ref/src/docbkx/ch_identity-v3.xml

@@ -22,7 +22,7 @@
     xlink:href="#identity-v3">
     <title>Identity Service API v3</title>
     <para>Gets an authentication token that permits access to the
-        Compute API for 24 hours.</para>
+        Compute API.</para>
     <section xml:id="Version_Calls">
         <title>Versions</title>
         <wadl:resources xmlns:wadl="http://wadl.dev.java.net/2009/02">