XD-148 Improve experience when Redis not running

- Log a friendlier message (minus giant stack trace)
when Redis is not available

- Print helpful message to console

- Remove redundant StreamServer launch method to
consolidate exception handling code
XD-153 Gauge module implementation

The code is essentially a copy of the RichGauge implementation
with the simpler Gauge type.
XD-153 Use stream name as default gauge name.

We don't want to have to supply a 'name' parameter every
time we create a gauge.