Update for CocoaPods 0.34

* Reworked xcconfig import situation to account for pods now installing their own.
* Changed the replacement Crashlytics key; the old one was escaped in the new XML project file, breaking tiramisu replacements.
* Bump xcconfigs
More small project tweaks.

Add xcconfigs as a folder reference, rather than groups; makes sure that newly added
files get included (e.g., iOS Frameworks, new with iOS 8).
Add a Frameworks group and move the pods static libraries there.
Enforce CocoaPods >= 0.34.1, and note that in the README.

Also clean up version checks in tiramisu.
Merge pull request #23 from crushlovely/cocoapods-3.4-fixes

Cocoapods 3.4 fixes