Merge pull request #26 from broadinstitute/irwin-bmtagger

Irwin bmtagger
Made test_taxon_filter.py not executable, so that it will be run by Travis; removed /usr/bin/env python from test_tools_bwa.py so as not to temp fate.
Merge pull request #27 from broadinstitute/irwin-fix_test_taxon_filter

Turned off executable bit on test_taxon_filter.py so Travis will run it.
Deleted scripts/__init__.py since the python files in scripts/ are not import safe.
Require executable bit not set for test/*.py so nose won't silently exclude them.