STORE-235 & STORE 141

Part 2 and 3 of the fixes to allow images to be visible by tenants.

STORE-235:
The issue was caused by a problem with the client script not initializing the tokenInput plug-in when the request for tags fail. (This has been added as a separate issue)

The issue was fixed by first checking if a tokenInput element is present before attempting to retrieve the tags selected by the user.

STORE-141
The storage security provider was cached in the application context and therefore once a tenant logs in it continues to use the registry and user manager from the previous user.

This was rectified by moving the Store storage security provider to the session and adding it to the managers object of the store script. This change also moved the caching of the provided tenant from application context to the session.

Store:
-Anon users can view images 
-Logged in tenants can view images of published assets