Added ace editor for body of gist file.
Supported ace text mode. Added ace as a submodule.
Wrote about git submodule on README.
Started using github code theme and 2 spaces for tab.
Made code editor responsible.
Use public git submodule URL.
Fix the installation section of README.
CHANGELOG for 1.2.0
Merge branch 'develop' into rails4
@shuhei on CHANGELOG
Merge branch 'develop' into rails4