modify format_data() to turn deviation data into a float rather than unicode
declare prediction and v fields in db to be type number.  seems to work fine with None value

add print to tdrun.py
re-work format_data() to differentiate between prediction data and measurement data and correctly format and return either one.
extend enroll_data() to check whether data is allready in db and whether or not we have new new values

if we can update something from null to a value, we do.  otherwise do nothing.

also check to make sure we are not writing None over previous data.