changed the HIERARCH Keywords and the import statements
filter VerifyWarning so it only appears once.
ignore specifically the adding a HIERARCH keyword warning
Merge pull request #13 from wkerzendorf/gmos/change_hierarch

changed the HIERARCH Keywords and the import statements
changed mask to unit8
fixed the section problems by implementing a simpler treatment
finished a simple implementation of mosaic. still needs the shift and rotation implementation
fixed up the mosaicing code to give back an HDUList
added chip gaps and distortions to the detector yaml file
fixed the instrument_id and binnings in instrument_setup
finished implementing the mosaicing function into GMOSPrepare
adding the MDF table reconstruction
finished MDF Table construction - working on cutting the slits
finished the image slicing and added the chipgaps to the mask.
finished the prepare task with image slicing. This completes the prepare task.
added a file for small utilities scripts
Ensure that prepare.correct_overscan properly updates CCDSEC and DETSEC
Still use subslices in prepare.prepare.
Move classes out of prepare.prepare to gmos_basics
Merge pull request #18 from mhvk/gmos/mdf_cut

Ensure that prepare.correct_overscan properly updates CCDSEC and DETSEC
Merge pull request #15 from wkerzendorf/gmos/mdf_cut

GMOS MDF Cut