Allow specifying checked state of inline checkboxes

At the moment, because the label is returned, we have no way of chaining the ```check()``` or ```uncheck()``` calls. Passing in a param to check or uncheck solves this. Defaults to ```false```, so it doesn't break any existing calls, and since that's the default behaviour anyway at the moment.
Merge pull request #32 from manavo/patch-1

Allow specifying checked state of inline checkboxes