Adding GetHeaders message and tests.
Adding Transaction message and tests.
Merge branch 'master' of https://github.com/jmacwhyte/BitcoinSwift into jmacwhyte-master

Conflicts:
	BitcoinSwift.xcodeproj/project.pbxproj
Merge branch 'jmacwhyte-master'
Adding a space after colons in method invocations to be consistent with other swift projects.
Removing extra messages in XCTAsserts that were only necessary before Xcode 6 beta improved test failure messages.
General style cleanup and test cleanup.
Fixing issue with connectionTimerDidTimeout:
Added Reject message.