Import a required module.  Address Issue #49

`softwareupdater.py` raises an exception when it tries to update its local time via NTP during an update.  The message logged is `[do_rsync] Unable to update ntp time. Not updating`, however, updating the time via NTP was found to be functioning correctly.  After some tracing and troubleshooting, the root cause of the NTP exception was found to be an import issue: `global name 'time_updatetime' is not defined`.  It appears `softwareupdater.py` has not been importing a required `time.r2py` module.  It is unclear how this module has been working correctly until now. (perhaps repy2 changed the way imports are handled?)  In addition to issues with exception handling, the `softwareupdater.py` unit tests produce different results after every invocation (temp files are not properly removed, processes killed, etc?)