Fixed method documentation

Added [in] and [out] to @param for each method.  Added some missing
parameter documentation.
Generalized the show* methods

These methods now take an image source that is used to access
the images.  This makes it easier to load images from disk.

The image source must have the following two methods:
getCcdImage(Detector, ImageFactory, binSize)
getAmpImage(AmpInfoTable, ImageFactory)
Scale gain by arbitrary function in amp image
Added ds9.Buffering to CCD bounding boxes render
Return None instead of exception

When calculating the raw CCD bounding box return None instead of
raising when the amps do not have raw data.
Fixed up docs to match new API
Add division from __future__

Now importing division from __future__ this is more in line with
the rest of the stack.  There are some limitations with this outlined
in DM-83.
White space changes and removed unused code
Changed binSize to be in binned pixels

This makes it easier to deal with binned images and makes
it more obvious what to expect from the border in the image
displayed in ds9
Updated docstrings to reflect intent of binSize
Documentation improvements from review of DM-766

Adds documentation about examples scripts to doxygen
of CameraGeom.  Also clarified some of the assumptions
in the utils docstrings.