unit-testing migrated to mocha

This is in response to lognormal/boomerang#40 

Before straying too far from the state boomerang is on your master branch, I'd love to see this code merged into it. 

Contained in this PR is an initial set of unit-tests migrated from YUI to mocha and chai. It does not cover all parts of the code yet but is definitely more than has been tested before using YUI.

Tests can be ruin using `grunt test` they are not yet completely working I supposed with the code but it already helped seeing some holes in the way some functions are written.

Thanks in advance!