InstData Import/GMT Picard: add downsample ratio mixin
Downsample Ratio: update the downsample ratio mixin to be like the objects with API
GMT Picard: make _downsample_ratio_is_required class method
GMT Picard/InstData Import Downsampl Ratio: made separate class for required downsample ratio; updated errors; added tests
InstData Import: rm comment from basic bam downsample test
Move the modules/tests in postprocessing to be under command
Move the modules/tests in postprocessing to be under command
Merge remote-tracking branch 'origin/master' into downsample-ratio-mixin

Conflicts:
	lib/perl/Genome/InstrumentData/Command/Import/Basic_bam_downsample.t
Merge pull request #27 from ebelter/downsample-ratio-mixin
Merge pull request #63 from dufeiyu/rm_postprocessing

Remove the VR/PostProcessing
Bugfix: CombineReports orders columns correctly

The previous test only covered the case where two columns
swapped indices.  The code was not correctly ordering the
columns when the column switch was more complex.  A more
complicated test case showed it was broken, and a small
change to the code fixed it again.