Require pysam>=0.21.0; fix mpileup call (#335)

changelog

updated changelog

Merge pull request #282 from sanger-pathogens/argannot_issue281

Fixed GitHub issue #281 - ARG-ANNOT Fails to Download

Merge pull request #280 from sanger-pathogens/cdhit_docker_fix_branch

Added default locale to docker file

Merge pull request #274 from sanger-pathogens/rt660940_add_spades_to_…

…docker

RT 660940 - add spades to docker file

Merge pull request #271 from sanger-pathogens/v2.14.1_bug_fix_branch

Backed out MANIFEST.in change, bumped release number to v2.14.1 and added fix for issue 263

Updated CHANGELOG for release v2.14.0

Merge pull request #260 from kpepper/bump_version_to_2.13.5

Updated CHANGELOG.md

Merge pull request #257 from kpepper/update_changelog_for_v2.13.4

Rebuilt CHANGELOG for v2.13.4