version 1.2 minor bug fixes and enhancements

@bradnerComputation I'd like to get bamliquidator 1.2 released soon.

Please comment on #42 and I'll get that added to the pull request Monday evening.

These are the issues fixed in this pull request:
* #43 bamliquidator_batch (calling bamliquidator_regions) fails on valid .bed file
* #40 bamliquidator_batch -m option for multiple files should add columns
* #37 consider adding an option to control the number of threads used by bamliquidator_batch
* #33 bamliquidator rounding error
* #31 prevent out of sync versions for bamliquidator_batch / bamliquidator_bins / bamliquidator_regions