Add additional tests
Add additional tests

This adds two tests.

The first test is to validate that two successive counter events will
increment a counter.  This is more about ensuring we can look up the
same metric twice in a row than checking increment functionality.

The second test verifies that the hashLabels function returns different
results when labels are changed.

Signed-off-by: Clayton O'Neill <7833bf63e3b444bee2fe361e4dae2494a492a313@github.com>

prometheus/statsd_exporter,prometheus/statsd_bridge