Removed settings/update.py and modified branson.py to reflect updates. No changes required for settings/default.py

Changed performance log to a simple rather than rotating file. The file needs to be cleaned up rather than rotated, or the 3-day lookback property breaks.

Changed admin and admin email to Branson (e.g., myself), so that I can get emails when the live box throws a 500.

Added migrations for gdb_pe robot cert and 'background' tag. Also added 'background' to the list of blessed tags in the settings module.

The IVORN must have a hash sign between the fixed part (the 'ivo' bit) and the event-specific part (the 'resource number', or in our case, the graceid).

Made changes to bring VOEvent closer in-line with what Mina and Peter are proposing. However, I still don't have their AlertVersion property. Nor do I have any of the analysis specific stuff, like ChripMass, frequency, etc.