Test validity of grammarMap.

For #143.
Update activation in lib/script.coffee
Update script.cson
Update README.md to use <kbd> for keymaps
Merge pull request #148 from erran/escape-keymap

Update activation in lib/script.coffee
Use @ reference for codeContext
Update spec/grammars-spec.coffee
Merge pull request #146 from rgbkrk/grammarspec

Test validity of grammarMap
Update grammars.coffee

Added MoonScript to the list.
Update README.md

Added Moonscript to the list of languages.
Merge pull request #151 from OttoRobba/master

Update grammars.coffee
Add @OttoRobba as contributor
Update CHANGELOG
Prepare 2.7.0 release
:memo: Better explain "Line [number] Based" runs