Added ability to register for receiving updated x, y coordinates from the 
matplotlib viewer when its circle is moved.
Introduced ImageReading class to associate a reading with an image after
it has been downloaded.
Merge branch 'master' into reals_proc
Added cutout to logger debug statement.
ImageReading now exposes x, y, ra and dec values.  The x and y values 
can be updated, in which case the ra and dec values will be lazily refreshed
with a call to wcs.xy2sky (call still to be implemented).
Added parse_cd and parse_pv functions to wcs module so it can extract
the values from astropy FITS headers.
Added parse_order_fit function to wcs module.
Implemented updating RA and DEC for an ImageReading object when the 
operator has adjusted the x and/or y values.
The data view no longer directly subscribes to IMAGE_CHANGED events.
Instead the controller tells it when to update (i.e. whenever the controller 
is told to display an image).  This simplifies the code and eliminates the 
problem of the first image not having its data displayed.
As a result of these changes, KeyValueListPanel no longer takes a callable 
to get its data.
Removed KeyValueListPanel class since it no longer provides additional
functionality over the ListCtrlPanel.
switch to using BZERO instead of BSCALE
Modified the submission to add capabilities and clearer logging.
Moved get_observed_magnitude method from DownloadedFitsImage to
ImageReading.
The UIModel now provides the updateable RA/DEC values instead of the 
static ones read from the input file.
Moved calculation of source point from UIModel to ImageReading.
Added get_astrom_header and get_fits_header methods to UIModel
and refactored.
Merge pull request #103 from drusk/data_panel_startup

Closes #102.
small tweak on populating zeropt/iq_ossos for consistency with development version. Remove later.
Added method to coordinate converters to obtain a second converter 
which makes the transformation back from the original's output 
coordinate system to its input coordinate system.
Added method to DownloadedFitsImage for converting from pixel 
coordinates to the observed coordinates.