Add tinycolor.readability and tinycolor.mostReadable functions.  Change readability to be based on W3C recommendations.  Add AMD/requirejs/define() module code.
updates for docs
always return a tinycolor from mostreadable
add qunit testing to grunts
fix issue #15 by causing 6 character hex as the default.
fix issue #13 by declaring secondcolor
add tests for issue #13 (toFilter)
grunt build
Merge branch 'master' into gh-pages