initial implementation of detector properties
finished detector readin
detectorproperties linked to ccd_detector on gmosmosrawfitsfile
Merge pull request #6 from wkerzendorf/gmos/detector_properties

Gmos/detector properties
fixed reading in of detector properties
fix again for the detector properties class. but works now
proj.science[0].chip1_detector
<detector id=11 ccdname=EEV 8194-19-04 xbin=2 ybin=2 gain=1.90>
First cut at adding SubtractOverscan, CorrectGain, and CombineHalves classes.
added initial sqlalchemy stuff
implemented subtract overscan and error determination as functions
first working version of GMOSPrepare
fixed a problem with chipx_detector and refactored GMOSDetectorProperties to GMOSDetector
add GMOSMask to the gmos/__init__.py
added GMOSCCDImage an NDData subclass
added meta to GMOSCCDImage reader and fixed some minor mistakes
Merge branch 'mhvk/gmos_subtract' of github.com:wkerzendorf/geminiutil into mhvk/gmos_subtract

Conflicts:
	geminiutil/gmos/gmos_basics.py