calabash dylib support - based off PR 463

Based off https://github.com/calabash/calabash-ios/pull/463

Updates the rake `build_server` task to run:

* make framework
* make frank
* make dylibs

The default behavior of `rake build_server` is to build the dylibs.  However, building the dylibs requires injecting several .xcspec files _directly into the Xcode.app bundle._   If you don't want to build the dylibs, you can use CALABASH_NO_DYLIBS variable.

```
CALABASH_NO_DYLIBS=1 rake build_server
```

Injecting the xcspec files into the Xcode.app bundle requires `sudo`.  

If you are building the gem for release, _you must build the dylibs_.

### Links

* Adds framework and frank make rules: https://github.com/calabash/calabash-ios-server/pull/55
* Adds dylib targets to calabash server Xcode project: https://github.com/calabash/calabash-ios-server/pull/52  (not yet merged).