chore(dependencies): upgrade `grunt` to v0.4.4

Closes #25
chore(dependencies): upgrade `grunt-contrib-concat` to v0.4.0
chore(dependencies): upgrade `grunt-contrib-jshint` to v0.10.0
chore(dependencies): upgrade `grunt-contrib-watch` to v0.6.1
chore(dependencies): upgrade `grunt-karma` to v0.8.2