Define mime types for all engine processors
Stub register_transformer
Register engines as transformers
Fix adding trail alias
Detect mimes types in extension check
Lookup logical path format ext from transformer
Avoid using hike trail aliases

Only work for extnames, not content types
Remove old alias extension
Merge branch 'master' into asset-content-negotiation

Conflicts:
	lib/sprockets/paths.rb
Merge branch 'master' into asset-content-negotiation

Conflicts:
	lib/sprockets.rb
	lib/sprockets/base.rb
	lib/sprockets/cached_environment.rb
	lib/sprockets/engines.rb
	lib/sprockets/environment.rb
	lib/sprockets/paths.rb
	lib/sprockets/processing.rb
	test/test_environment.rb
Merge branch 'master' into asset-content-negotiation
Merge branch 'master' into asset-content-negotiation

Conflicts:
	lib/sprockets.rb
	lib/sprockets/base.rb
	lib/sprockets/cached_environment.rb
	lib/sprockets/engines.rb
	lib/sprockets/environment.rb
	lib/sprockets/mime.rb
	lib/sprockets/paths.rb
	lib/sprockets/processing.rb
	test/test_engines.rb
	test/test_environment.rb
Anchor Sass::Importers::Filesystem to root, fixes #599
Merge pull request #600 from amccloud/root-sass-importer

Anchor Sass::Importers::Filesystem to root, fixes #599
Merge branch 'master' into asset-content-negotiation

Conflicts:
	lib/sprockets.rb
Merge branch 'master' into asset-content-negotiation

Conflicts:
	test/test_engines.rb
Move resolve to its own concern

Shouldn't be exported globally
Only support resolve accept:
Tweak resolve error message
Use proper q value parser