Add authentication support
Tame NSQDConnection constructor parameter list

* Use an options parameter for all optional parameters for
NSQDConnection and WriterNSQDConnection
Revert using options for NSQDConnection
Remove options for NSQDConnection in Writer
Shorten authSecret valid check
Add back null check for authSecret
Make the conditional check for authSecret clearer
Merge pull request #32 from dudleycarr/feature-auth

Add authentication support