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

* Update Objective-C rules for .gitignore file. [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 >> Search Paths >> Frameworks Search Paths >> ```ld: warning: directory not found for option '-F/Users/mmt/Dropbox/UnderGoing/AnimateButton'```

![error](https://cloud.githubusercontent.com/assets/5597604/4730409/12977436-5999-11e4-8979-217fd50cfe77.png)

![screen shot 2014-10-21 at 6 40 28 pm](https://cloud.githubusercontent.com/assets/5597604/4730414/368ed7ee-5999-11e4-905c-c5ec138e67a8.png)