Front end changes for implementing plugin framework

Move templates and static files into corresp dirs under their app
Static files moved to storageadmin/static/storageadmin
Templates moves to storageadmin/templates/storageadmin
Modify static files url in base.html and nginx.conf.in
Staticfiles config changes

Only use AppDirectoriesFinder since all assets are under storageadmin
app
Correct path for pipeline_js for storageadmin assets
Correct path in base.html for js libraries
Correct paths for css and js
Framework for backup plugin and install mechanism
Plugin framework

Models, views and serializers for plugins and installed plugins
Db migrations for plugins and installed plugins
Load installed plugins in home.py
Generate js and css includes for installed plugins in base.html
Add activation key and installation message
Add close button and icon to modal
Add Backup plugin js and jst files...
Modify js and jst files for backup plugin implementation to work.
Add policy table jst file.
Write models js for bakup app.
Modify models js for backup app.
Add cancel event for add_backup_policy jst file.
Backup plugin

Add display_name, description to plugin and install date to
installed_plugin
Modify Backup policy form
Add backup db and first migration
Add view and serializer for backup app
Backup view and url

Add django url for backup plugin
Load BackupPolicyCollection in backup view
Add generic_view for backup app
Add wal mode for backupdb in buildout
Backup policy

Fixes for backup policy form to save correctly
Merge branch 'master' into issue#408_plugin_framework

Conflicts:
	conf/settings.conf.in
	src/rockstor/storageadmin/static/storageadmin/js/models/models.js
	src/rockstor/storageadmin/static/storageadmin/js/router.js
	src/rockstor/storageadmin/templates/storageadmin/base.html
	src/rockstor/storageadmin/views/home.py
cleanup buildout configuration and change download recipe for js-libraries.