Rename the interface to barbican-hsm

It was called barbican-hsm-plugin, but it was decided to rename it to
barbican-hsm.  Also added a README and ensured that the tox -e pep8 target
passes.

README.md

@@ -0,0 +1,43 @@
+# Overview
+
+This interface supports the integration between Barbican and HSM devices.
+
+# Usage
+
+No explicit handler is required to consume this interface in charms
+that consume this interface.
+
+The interface provides `hsm.connected` and `hsm.available` states.
+
+## For an HSM subordinate charm
+
+The `hsm.connected` state indicates that the Barbican principle charms has been
+connected to.  At this point the plugin data required for to configure the HSM
+from Barbican should be presented.
+
+# metadata
+
+To consume this interface in your charm or layer, add the following to `layer.yaml`:
+
+```yaml
+includes: ['interface:barbican-hsm']
+```
+
+and add a provides interface of type `hsm` to your charm or layers
+`metadata.yaml`:
+
+```yaml
+provides:
+  hsm:
+    interface: barbican-hsm
+    scope: container
+```
+
+Please see the example 'Barbican SoftHSM' charm for an example of how to author
+an HSM charm.
+
+# Bugs
+
+Please report bugs on [Launchpad](https://bugs.launchpad.net/openstack-charms/+filebug).
+
+For development questions please refer to the OpenStack [Charm Guide](https://github.com/openstack/charm-guide).

interface.yaml

@@ -1,4 +1,4 @@
-name: barbican-hsm-plugin
+name: barbican-hsm
 summary: Interface for a plugin to the Barbican charm.
 maintainer: OpenStack Charmers <openstack-charmers@lists.ubuntu.com>
-repo: https://github.com/openstack-charmers/charm-interface-barbican-plugin
+repo: https://github.com/openstack-charmers/charm-interface-barbican

provides.py

@@ -15,11 +15,10 @@
 import json
 
 import charms.reactive as reactive
-import charmhelpers.core.hookenv as hookenv
 
 
 class BarbicanProvides(reactive.RelationBase):
-    """This is the barbican-{type}hsm-plugin end of the relation
+    """This is the barbican-{type}hsm end of the relation
 
     The HSM provider needs to set it's name (which may be relevant) and
     also provide any plugin data to Barbican.
@@ -38,16 +37,16 @@ class BarbicanProvides(reactive.RelationBase):
     # with a basic documentation string provided.
     auto_accessors = []
 
-    @reactive.hook('{provides:barbican-hsm-plugin}-relation-joined')
+    @reactive.hook('{provides:barbican-hsm}-relation-joined')
     def joined(self):
         self.set_state('{relation_name}.connected')
         self.set_state('{relation_name}.available')
 
-    @reactive.hook('{provides:barbican-hsm-plugin}-relation-changed')
+    @reactive.hook('{provides:barbican-hsm}-relation-changed')
     def changed(self):
         pass
 
-    @reactive.hook('{provides:barbican-hsm-plugin}-relation-{broken,departed}')
+    @reactive.hook('{provides:barbican-hsm}-relation-{broken,departed}')
     def departed(self):
         self.remove_state('{relation_name}.available')
         self.remove_state('{relation_name}.connected')

requires.py

@@ -15,7 +15,6 @@
 import json
 
 import charms.reactive as reactive
-import charmhelpers.core.hookenv as hookenv
 
 
 class BarbicanRequires(reactive.RelationBase):
@@ -35,16 +34,16 @@ class BarbicanRequires(reactive.RelationBase):
     # with a basic documentation string provided.
     auto_accessors = ['_name', '_plugin_data']
 
-    @reactive.hook('{requires:barbican-hsm-plugin}-relation-joined')
+    @reactive.hook('{requires:barbican-hsm}-relation-joined')
     def joined(self):
         self.set_state('{relation_name}.connected')
         self.update_status()
 
-    @reactive.hook('{requires:barbican-hsm-plugin}-relation-changed')
+    @reactive.hook('{requires:barbican-hsm}-relation-changed')
     def changed(self):
         self.update_status()
 
-    @reactive.hook('{requires:barbican-hsm-plugin}-relation-{broken,departed}')
+    @reactive.hook('{requires:barbican-hsm}-relation-{broken,departed}')
     def departed(self):
         self.remove_state('{relation_name}.connected')
         self.remove_state('{relation_name}.available')