Added a check to see if a .fz version of the image exists.

get_image looks for a number of different possible locations for files.
Files that are coming as links from the archive come in .fz format,
so we're looking for those too now.
Made the --force flag do something
Raise an error when photometry fails instead of returning -1

The old way of doing this was to send a -1 back, but now the
daophot package provides multiple return values (xcen, ycen, mag, merr)
so sending back a -1 doesn't make sense.  Really, raise should have
been the process all along.
Remove the restriction of MERR and raise a more useful message.

The previous daophot would not return a magnutude if MERR was
large. But large is a relative term.  So, now daophot returns
a magnitude if no errors were raised, even if that value has
a large uncertainty. The uncertainty is sent back too, so
the downstream user can decide what to do.

Also, task error message that was sent with errors was not
very specific. Now its a bit clearer.
Reorder columns and added a '#' to the column header rows.

Jean-Marc uses code that wants the columns in a particular order, so
we are providing that.  He also wants a '#' on the row that has
the column names, we now provide that too.

Also added a dry-run flag and some format cleanup for the header.
Make keeping intermediate files the default behaviour.

I was trying to diagnose that problems with PSF offsets and that
would have been easier if we kept the intermediate files.
These are things we need to install for ossos pipeline
Trying to get a travis build working... ish
Merge branch 'master' of https://github.com/ijiraq/MOP