More complex than I had hoped for, to add
Temperature I needed to;
* introduce two new metrics Avg/Max temperature
* adjust metric conversion to include a conversionSum
for the C to F conversion
* handle temperature as a metadata field as well as a
ride data series
* handle the RideFile::noTemp value rather than just
averaging or calculating max.
Fixes#603.
Adds error checking to Tweet Ride. Checks to make sure that oauth
credentials exist, that tweet is under 140 characters, and that
oauth_http_post received a reply indicating a successful post.
Move addition of hashtag to getTwitterMessage() to cleanup length
calculations.
