periodic sampling of cpu metric broken
Added exometer:aggregate/2
allow 'default' in aggregate/2; added test case
improved histogram docs
add {histogram,Vs} op to evaluator
add exometer_util:histogram/[1,2]
add exometer:ensure/3 & select_count/1
add 'total' to histogram
add Total to get_statistics2() call
Merge pull request #69 from Feuerlabs/uw-minor-additions

Uw minor additions
add module default for meter
enable/disable reporters + bug fixes
fix status output in info calls
Merge pull request #71 from Feuerlabs/uw-minor-additions

Uw minor additions
collectd reporter retry limit + bug fixes + docs
missing function clause
setopts bug for probes
deadlock in spawn_reporter
Merge pull request #72 from Feuerlabs/uw-collectd-retry-limit

collectd reporter retry limit + bug fixes + docs
setopts callbacks return ok