Updated FontAwesome to 4.2.0

git-svn-id: https://plugins.svn.wordpress.org/socials-ignited/trunk@979776 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added sanitization for the Opacity value.

git-svn-id: https://plugins.svn.wordpress.org/socials-ignited/trunk@979834 b8457f37-d9ea-0310-8a92-e5e31aec5664
Changed version to 1.7.3

git-svn-id: https://plugins.svn.wordpress.org/socials-ignited/trunk@979837 b8457f37-d9ea-0310-8a92-e5e31aec5664
Changed stable tag to 1.7.3

git-svn-id: https://plugins.svn.wordpress.org/socials-ignited/trunk@979854 b8457f37-d9ea-0310-8a92-e5e31aec5664