Replace swiftz_core with LlamaKit
Use ReactiveCocoa/LlamaKit for important fixes
Re-add our own `identity` function
Migrate to LlamaKit, fuck up all build settings
++xcconfigs for jspahrsummers/xcconfigs#29
++xcconfigs
Merge pull request #1505 from ReactiveCocoa/llamakit

Migrate from swiftz to LlamaKit