Stats: break out job runtimes and counts by result

For every job completed, record the result of that job separately
to statsd.  For successful and failed jobs, record the runtimes
of the jobs separately by result (others are not interesting).

Also, substitute '_' for '.' in job names in statsd keys.

This is backwards-incompatible with current statsd keys.

Change-Id: I7b6152bcc7ea5ce6e37bf90ed41aee89baa29309
Merge "Stats: break out job runtimes and counts by result"