Merge pull request #28 from diascreative/master

Merge action2020 features e.g. image clearing
Spontaneous.init should return the site instance
Allow for mounting Rack apps into the back, not just Sinatra apps
Fix Fog deprecation warning
Add a default proc to prototype set
Pages should recognise their own outputs
Symbols should select as UIDs
Page controllers are now full Sinatra instances.

This along with consistent inheritance for the controller classes allows site-wide configuration
of request handlers (e.g. for session config & middleware). Fixes #27
Split responsibilities of #show & #render calls

and test all the parameter combinations
Accept box & type filtering in the navigation helper

Fixes #21
Insert front applications into preview
Move to 1.9 style hashes
Allow mounting custom apps under custom path prefixes