* [password] _random_password -> random_password and moved to util/encrypt.py
* [passwordstore] Use built-in random_password instead of pwgen utility
* [passwordstore] Add integration tests
* Sort packages to install.
* Add python-argparse to centos6 docker image.
* Add gcc and python dev lib to docker images.
* Add python cryptography to docker images.
* Add coverage using pip instead of OS packages.
* Update old pip versions in docker images.
* Exclude */pyshared/* from coverage reporting.
