Fix Issue #10 and `ld: warning`. Update .gitignore.

* Update Objective-C rules for .gitignore. [source](https://github.com/github/gitignore/blob/master/Objective-C.gitignore)

* Fix error [(Issue #10)](https://github.com/mrcrow/MRoundedButton/issues/10). Update UI_APPEARANCE_SELECTOR tag.

* Remove path from Build Settings >> Frameworks Search Paths >> ```ld: warning: directory not found for option '-F/Users/mmt/Dropbox/UnderGoing/AnimateButton'```