Remove Pods references for libAsyncDisplayKit.a

I was trying to build AsyncDisplayKit as a static library, and couldn't see why things depended on a `pod install` to be run, so, I went through its project.pbxproj file and removed any references to the Pods build phases. I also removed an `#import` of OCMock from ASTextNodeTests.m.

Everything still builds with these changes, and after adding `-ObjC` to `OTHER_LDFLAG`s of the Tests build target, all of the tests still pass.

That said, I don't have Cocoapods installed on my machine (some of the things I build are very picky, and, I try not to rock their boat too much), so I wasn't able to test building any of the example apps after my changes. I _think_ that everything is okay — I didn't touch the .podspec for the project — but, I did update the Podfile (and Podfile.lock — which sounds like its normally machine generated — whoops), and I'm not entirely sure what role they play in everything.