libxml2 writes this file a bit differently
General cleanup and more robust catching of exceptions
Make ongoing stats collection for a check uniform across all checks.
Almost every check carries a stats_t in it's check closure that it
populates and in it's final phase sets that stats structure use
noit_check_set_stats.  Instead of every check doing this its own
unique way, we introduct and "inprogress" stats_t structure into
the noit_check_t.stats structure so that all checks can do it the
same way.

This change also improves the console and xml outputs showing checks
to include the "inprogress" metric data.
Merge branch 'master' of github.com:circonus-labs/reconnoiter