change the class used for the selector so that it wont' conflict

I found that using only "dropdown-toggle" as the selector would conflict is real bootstrap menus were in use in the navbar.  By changing the selector to something unique this problem goes away.
Merge pull request #12 from windbender/master

In the readme, for the dropdown example, change the class used for the selector so that it won't conflict with other uses of "dropdown-toggle"