Travis config.
This is not linux dorothy.
make me a sandwich
Install library dependencies in script/bootstrap
Warn about Homebrew prefixes that aren't /usr/local
Overhaul README, reference script/bootstrap
Skip installed packages
Merge remote-tracking branch 'origin/master' into travis-config

Conflicts:
	External/Configuration
	External/openssl
Merge pull request #258 from libgit2/install-deps-in-bootstrap

Install dependencies in script/bootstrap, overhaul README
Merge remote-tracking branch 'origin/master' into travis-config
Fix campfire notifications.
Merge pull request #247 from libgit2/travis-config

Use Travis CI
Merge branch 'master' into git-cred