Handling nulls properly when creating pie chart. Ready for testing. 

This commit also includes a reversion of a mistake I made in combining
the CSS for all media queries into one section in the CSS. I've
separated the CSS per query again, working back from history.
Added jasmine specs for new legend creating functionality
Merge pull request #216 from isuftin/NAWQAAN-312

Handling nulls properly when creating pie chart. Ready for testing.