+ Filestore listing filtered by user view permissions
+ Configuration help for filestore relocated to website files
+ Added migration example

+ Adds standard logging for all authentication providers
+ Updates help page to use default GitBlit SSH port

The RPC URL should be `/rpc/?` and not `/rpc?` according to
https://groups.google.com/d/msg/gitblit/Ajp2gR3B2bM/AXg6wIf21eIJ

In AuthenticationManager:385, only `provider instanceof UsernamePasswordAuthenticationProvider` will be called

This change also ties the plugin manager into the Wicket framework and
allows plugins to contribute and mount new pages which are linked by the
top navbar and repository navbar extensions.

To allow for integration of 3rd party server monitoring solutions,
Gitblit needs to expose an extension point for collecting http data.