Moved MPCWriter import to the function where it is used so that the 
mpc module does not get loaded unless it is needed (i.e. we are in the
reals task).  This is in an effort to reduce startup time.  mpc adds a 
significant overhead due to the fact that it import astropy modules for 
formatting ra and dec.
Moved daophot import to the method where it is used so that IRAF is not
loaded unless needed.  This improves startup time for processing 
candidates.
Force iraf load up front in process reals task to avoid lag when accepting
first source.
Merge pull request #90 from drusk/optimize_startup

Closes #89.