Add Carthage and Framework Support

[Jeehut]

This adds support for Carthage framework inclusion. Just put github "jmenter/JAMSVGImage" "develop" into the Cartfile and run carthage update (or drop the "develop" for the latest stable release version later on).

Note that we should add instructions on how to install this via Carthage including the fact that inclusion is done via the Umbrella file like this: #import <JAMSVGImage/JAMSVGImage-Umbrella.h> – the JAMSVGImage name was already used so I had to create a custom Umbrella file. We could also rename the JAMSVGImage file to keep the default umbrella file name given by XCode.

Also note that I renamed the existing JAMSVGImage target which includes an example project to JAMSVGImage Example and created a new scheme for it. I already included JAMSVGImage as a framework within the example project but it only built in the Simulator for me – we should fix that in the near future, too.

Specifically done in this request:

• [x] Add iOS and tvOS targets
• [x] Add Test targets
• [x] Restructure project files
• [x] Add custom modulemap for umbrella file
• [x] Add shared scheme for building with Carthage

TODOs (can be done after the merge):

• [ ] Add installation instructions via Carthage to README
• [ ] Fix example project to run on real devices

[Jeehut]

@jmenter Any thoughts on merging this?

[jmenter]

Thanks! This is a pretty major change, I'd like to check it out further before adding just so I know what's going on. I think I'll have some time on Friday.

[Jeehut]

@jmenter Found any time to have a look at this? I'm still using my fork for building with Carthage and Carthage is now used quite a lot.