do a distclean as the CFLAGS may have changed. Fixes #442
Merge pull request #453 from ged-lab/fix/zlib-config-reset

always run zlib's configure; CFLAGS may have changed
support running tests after install
move towards a unified exception hierarchy
clean up exception handling for hash_{consume_fasta,abundance_distribution}
run scripts & test data via pkg_resources
include fallback for get_test_data
try the local scripts directory before $PATH
silence some compiler warnings
fix script search paths
only run the script once
pep8 cleanup
add changelog, update URL for sphinx-contrib