Merge pull request #51 from hashd/master

Changes to pie, donut and line chart
Merge pull request #52 from hashd/master

Compress task added to Grunt taskrunner
Merge pull request #53 from hashd/master

Modified gitignore to avoid committing gh-pages files on master branch
Merge pull request #57 from hashd/master

Update palettes, grunt tasks and contributors list
Fix for polar area chart.
Added circle ticks for polar area chart.
Merge pull request #62 from priyankadudani/master

Adding Polar area chart fixes.