Move dependencies into the gemspec to ease upgrades

but leave big/optional installs in the Gemfile i.e.
- The ExecJS implementation
- The ruby Xapian bindings
The war against double quotes continues
Sign gem
Don't crash if the simultaneous server isn't running
Remove Rack::Lint from the editing middleware
Move Image field support modules into separate files
Refactor image fields & move image processing to skeptick
Add .ruby-version & .ruby-gemset files to the ignores
Make test work across ruby versions

v2 escapes single quotes too
De-clutter the file/image processing pipeline
Merge branch 'master' of github.com:SpontaneousCMS/spontaneous
Merge branch 'skeptick'