less generic jquery extensions

i've been running into a handful of problems because this plugin creates, and uses, the following methods:

* addTag
* removeTag
* tagExist
* importTags

these are fairly generic method names, and have been creating namespace collisions with a handful of other plugins I've used.

I'd like to suggest renaming these methods as such ( patch enclosed ):

* tagsInput_addTag
* tagsInput_removeTag
* tagsInput_tagExist
* tagsInput_importTags

this keeps (most) other packages from namespace collisions with tagsinput ( and vice-versa )

also. some space formatting changes got in there.