package.json: set required Node.js version to 0.8.x
amberc.js: make Node.js 0.8 compatible

replace:
path.exists -> fs.exists
path.existsSync -> fs.existsSync
amberc-grunt.js: make Node.js 0.8 compatible

replace:
path.existsSync -> fs.existsSync
amberc-grunt.js: make Node.js 0.8 compatible

replace:
path.exists -> fs.exists
path.existsSync -> fs.existsSync
grunt: move pegjs task into separate file
grunt: rename pegjs task to peg (grunt conventions)
grunt: rename amberc-grunt.js to grunt-amberc.js
grunt: extract css2js task into separate file
grunt: rename grunt.js to Gruntfile.js (grunt 0.4 change)
grunt: use grunt 0.4 and latest jshint plugin
grunt: replace <json:> directive with readJSON()
grunt-peg.js: use this.options introduced in grunt 0.4
README: update build instructions for Grunt 0.4
travis.yml: install grunt-cli before running tests
Clarify installation of Grunt.js
Merge pull request #435 from mkroehnert/grunt-0.4

Update to Grunt.js v0.4 and require Node.js v0.8