UDP support 

Added the following:
1. Added UDP support
2. Added equals method for DatadogSeries
3. Removed http related arguments (apiKey, socket timeout, connection timeout) etc from DatadogReporter builder. As these are applicable only for http, and having it part of the reporter would give users the wrong impression that they may be applicable for udp too.
Hmm... I'd prefer keeping HttpTransport as the fallback for backward compatibility.  Some clients of this library may be building the reporter without setting the transport.  That said, if we really want to break compatibility, I'd prefer throwing an exception here. In detecting programming errors, I prefer compileTime > initializationTime > runtime :)