Extract BW::HTTP to the bubble-wrap-http gem

Also prints out the following message when building your app:

```
$ rake
   Warning BubbleWrap::HTTP is deprecated and will be removed - switch to a different networking library soon (see https://github.com/rubymotion/BubbleWrap/issues/308).
   Warning You can use the 'bubble-wrap-http' gem if you need compatibility: https://github.com/rubymotion/BubbleWrap-HTTP
     Build ./build/iPhoneSimulator-7.0-Development
```