Merge pull request #42 from uber/update-version

Updates version to 2.5.1

Merge pull request #28 from uber/artman/swift

Adds default implementations for default signal types using concrete signal classes.

Merge pull request #24 from uber/swift-support

Support Swift

Merge pull request #20 from uber/artman/podspec

Set podspec iOS target back to 7.0

Merge pull request #15 from uber/tuomas/bump-podspec

Bumping podspec

Release 2.1.0

Merge pull request #10 from uber/void-empty-signal

Empty signal's fire-method should have void parameters so as error out if someone passes in arguments

Merge pull request #8 from uber/artman/weak-tests

Added tests to verify that listener is not retained.

Updated podspec to MIT license

Updates podspec to point to correct license file