Append Croogo plugin path to app default paths

- easier paths for view/elements and layouts
- backward compatibility
Create Croogo plugin for common code across plugins
CS Fixes
Specify database as 'test' in AclExtras
Moving Croogo bake templates to the Croogo plugin
Finishing moving views and assets to Plugin
Fixed Croogo plugin tests and add it to the test suite
Moved Croogo bootstraping in Croogo plugin
Remove extra DS
Fix: App::path() is reset at setUp()

We now have 2 test_app directories for different purposes, thus path
needs to be reset everytime.  Tests needing special path will need
to do its own housekeeping in their setUp().
Move CakeErrorController to CroogoErrorController
Add plugin name when appropriate
Fix: undefined variable $plugin
Move theme assets and generation tools
Merge branch '1.5-common-plugin' into 1.5

Closes GH-124