usdriver.py -- added option to switch server access on and off.
usdriver.conf -- changed server name

Less ULTRACAM specific
drivers.py -- added checks against server access, removed start button

Start button now part of uspec.py. Various checks added to prevent attempts to access the server if not wanted.
uspec.py -- Post gone, Start added

Now single Start button does what used to be accomplished with Post and Start. This is to ensure that any RA, Dec information is current.