add ace to make json editable, and bugs fixed.
use Grunt.
add json preview mode.
Revert "add json preview mode."

This reverts commit 269124e04172c6487f5cc90c73186ed1c822c1ff.
add json preview mode.
revert commit b0194bc
use jshint.
auto generate extension version.
auto generate zip package.
add json revert, export & import function.
replace keypress with keydown for closing frame event.
redesign the icon.
add timestamp to released zip file
Merge branch 'dev'