Update test/installation documentation

This updates testing and installation documentation
for Patrole. Specifically:
  - Add unit test execution information
  - Add DevStack plugin information

Change-Id: Ic3c5b307152da0da16237fc196f2f6f0edba99ff
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index e342dd8..31f94f4 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -7,6 +7,7 @@
 
 At the command line::
 
+    $ git clone http://git.openstack.org/openstack/patrole
     $ sudo pip install patrole
 
 Or, if you have virtualenvwrapper installed::
@@ -19,6 +20,17 @@
     $ navigate to patrole directory
     $ sudo pip install -e .
 
+DevStack Installation
+=====================
+
+Patrole can be installed like any other DevStack plugin by including the
+``install_plugin`` directive inside local.conf::
+
+    [[local|localrc]]
+    ...
+
+    enable_plugin patrole git://git.openstack.org/openstack/patrole
+
 Configuration Information
 =========================