Remove threads.h from module map

It doesn't exist anymore.

Merge pull request #443 from phatblat/ben/pr/libgit2-build

Fix libgit2 build scripts

Merge pull request #440 from phatblat/ben/pr/push2

API changes for push in libgit2 0.22

Merge pull request #433 from libgit2/pacify-xcode

Pacify Xcode

Merge pull request #431 from libgit2/carthage-0.5

Migrate to Carthage 0.5

Merge pull request #428 from libgit2/update-tracking-branch

Update tracking branch

Remove USER_HEADER_SEARCH_PATHS setting

Merge pull request #421 from libgit2/cartfile

Use Carthage to manage submodules

Lotta stuff

Initial tag