bump tilt requirement, unregister plaintext template. fixes #824
prep
changelog
Remove Rainpress pure ruby CSS compressor and simply use SCSS :)
Merge remote-tracking branch 'upstream/3.0-stable'

Conflicts:
	Gemfile
	middleman-core/lib/middleman-core/version.rb
	middleman-core/middleman-core-x86-mingw32.gemspec
	middleman-more/lib/middleman-more/extensions/minify_css.rb