adds 64 bitness to calabash.framework

## Motivation

https://github.com/calabash/calabash-ios/issues/313 - thanks @daudt

- [ ] has a companion pull request on the gem side

The target iOS version was iOS 4 - a version that we dropped support for some time ago. 

This pull request sets the minimum iOS version at 5.1.1 and builds the calabash.framework with an arm64 and x86_64 slice.

In order to upgrade the min iOS version and include 64-bit slices, I needed to implement a new strategy for building the framework. 

I spent a fair amount of time exploring the next Xcode version and the consequences of bumping the min iOS version.  All seems well.  I was able to execute tests using that Xcode version against iOS 5.1.1, 6.1, and 7.0.*  devices as well as on the test cloud.  There were hiccups testing against the simulator, but those hiccups exist independent of the state of the calabash.framework.

## Testing

Xcode 5.0.2

### Briar

* [briar 0.1.4.b2](https://github.com/jmoody/briar/tree/0.1.4.b2)
* [briar-ios-example](https://github.com/jmoody/briar-ios-example/)

###### NO_LAUNCH=1 ==> Manually Launching ==> UIA _not_ available

- [x] iPad 1 iOS 5.1.1
- [x] iPhone Simulator iOS 6.1

###### NO_LAUNCH=0 ==> Launching with Instruments ==>  ==> UIA available

- [x] iPad 4 iOS 7.0.3
- [x] iPhone Simulator iOS 7
- [x] iPhone Simulator iOS 7 64-bit

### XTC

- [ ] Apple iPhone 4S (5.1.1)  ==> not finished yet
```
Apple iPad 2 (6.1.3)
Apple iPad 4th Gen (7.0.4)
Apple iPad Mini Retina (7.0.4)
Apple iPhone 4S (6.1.3)
Apple iPhone 4S (7.0.4)
Apple iPhone 5 (7.0.4)
```

### ruby version smoke testing

[LPSimpleExample](https://github.com/jmoody/calabash-ios-example)

- [x] ruby 2.0 
- [x] ruby 1.9 
- [x] ruby 1.8 - had to use rest-client 1.25 because of https://github.com/calabash/calabash-ios/issues/280