Param Setup: Fix for #332, arduplane.pdef.xml being deleted when there is no internet connection

We now test to see if the download request fails or succeeds, and only
open/truncate the file if it succeeds. On failure a QLOG_ERROR() message
is outputted to the log.
Full Param Setup: Fix #321, added factory reset button to reset all parameters

This button sets FORMAT_VERSION to 0, and reboots the UAV after confirming
with the user that they actually want to reboot.
Graph View: Fix MODE display not showing up properly in mouse-over