Fixes for TableTools to work with Bootstrap

The z-index of .dropdown-menu li defaults for 1001 in Twitter Bootstrap. 
This causes .DTTT_collection_background to cover buttons from TableTools plugin.
I've added necessary fixes to make the plugin work with bootstrap using the default configuration from http://datatables.net/release-datatables/extras/TableTools/bootstrap.html
Merge pull request #36 from matfiz/master

CSS fix for TableTools play smoothly with Bootstrap