Add note on contributing

It's really useful for contributors to know of the automated process in place for testing out contributions.
Merge pull request #50 from serra/patch-1

Add note on contributing
Update src/Bootstrap/BootstrapSupport/ControlGroupExtensions.cs

Fixed bug where was control group helper was not writing the closing div.
License updates per twitter conversation with Eric Hexter on twitter.
Merge pull request #55 from trayburn/master

Adding Apache License
Merge pull request #54 from AgentShark/patch-1

Bug with control group helper not writing the closing div.
Fixed invalid JSON parsing for empty attributes

An empty string (or null object) is invalid JSON, and needs to be
converted to a 'null' string. jQuery 1.9.0 has exposed this previously
accepted JSON. Now we need to convert it.

http://forum.jquery.com/topic/parsejson-in-1-9-0-is-different-from-earlier-versions
Currently, if using jQuery 1.9.0, this code will throw an exception when
dealing with empty validation attributes.
Merge pull request #59 from joshball/master

Fixing invalid JSON when parsing empty attributes
Merge branch 'master' into html_helpers_paging