Merge pull request #61 from mooz/master

Array.form -> Array.from
Update escodegen's version
Update escope's version
version 0.0.11-dev starts
Not distinguish between null and undefined in ReturnStatement#argument

Close #64
Use package.json's version number
version 0.0.12-dev starts
Update escodegen version 0.0.20
version 0.0.13-dev starts
Add concatenate-variable-definition pass. Close #65
Add missing common.unreachable() to constant evaluator
Merge pull request #67 from jaens/master

Cleanup: consistently use common.unreachable();
Update estraverse version to 1.0.0
Merge branch 'master' of github.com:Constellation/esmangle
Make code JSHint clean
Use grunt to build / test files
Use mocha directly
Fix travis versions
Add colors
Pass color and spec reporter option to mocha