Added Source Sans Pro Bold and according css support
added source sans font weights: light(300), semibold(600), bold(700)
Merge pull request #16 from sodevious/master

Added Source Sans Pro Bold and according css support
added more font weights added them to the same font family
Merge pull request #17 from opensourcedesignis/bold-issue-15

added source sans font weights: light(300), semibold(600), bold(700)
Merge branch 'master' into links
rebasing with latest master changes