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.
The indentation on these lines is a bit misleading (looks like unbalanced parens at a glance). Perhaps change it to:
```
request.addGauge(new DatadogGauge(
    maybeExpand(Expansion.MAX, name),
    toNumber(convertDuration(snapshot.getMax())),
    timestamp,
    host,
    tags));