Improving iOS 7 bubbles, eliminate 2 compiler warnings, disable datadetectors in simulator

~~I adjusted the bubble-min images to have corner radii more closely matching iOS 7’s~~, and attempted to get them a bit sharper looking. Adjustments made to insets to sharpen up the appearance of the bubble on the top/right edges. Adjusted x and y position of the textview frame to improve padding and position text more closely to vertical center (this part’s kind of a hack… probably a better way than just hard-coding +4 and +3!) 

*UPDATE: I reverted my changes to the images themselves, after I realized you had actually pulled these from iOS itself. So the main contribution I made to the bubbles now is just improving the insets and padding. It still seems to me that the corners of the bubbles don't appear as sharp as they do in iOS 7 Messages app, for some reason.*

Here's a before/after gif:

![output_yvfvfy](https://f.cloud.github.com/assets/127062/1798769/d51bcf42-6b6b-11e3-9203-dc62a7996922.gif)

(BTW, am I crazy, or does the text seem a bit 'soft', especially the white text on blue bubbles?)

Eliminated a couple of compiler warnings I was receiving, one of which was due to compiling for 64-bit. 

Disabled data detectors when running in the Simulator, as this seems to crash with EXC_BAD_ACCESS quite a bit.

BTW, thanks for building this. :+1: