python-augeas from PyPI

https://github.com/hercules-team/python-augeas/issues/2#issuecomment-64116945
Refactor clients module.

- PEP8, pylint cleaning

- no-self methods -> functions, some of which were moved to acme or
  challenge module.

- a bit of renaming

- more Pythonic code

- Sphinx-like doc.
Simple doc fix in configurator
Clean crypto_util, add some doc
Merge pull request #64 from kuba/pypi-augeas

python-augeas from PyPI
apt-get install libaugeas0

libaugeas0 is still required, despite python-augeas from PyPI
Merge pull request #69 from kuba/libaugeas0

apt-get install libaugeas0
LetsEncryptClientError
Less generic exception for subprocess.check_call.

https://docs.python.org/2/library/subprocess.html#exceptions
Less generic exception catching in send()
Merge pull request #60 from kuba/acme_test

Add acme_test. Sphinx-like doc in acme module.
le_util cleanup, le_util_test
Fix JOSE encoding mess
Better tests for jose b64 padding
Allow unicode input for JOSE Base64
Fixed typos in crypto_util.py
Bring in @Kuba PEP-8 BranchMerge branch 'kuba-pep8'
Remove heisenbug from acme_test
py26 doesn't support set {} constructor. Use frozenset.
Merge remote-tracking branch 'github/master' into le_util_test

Conflicts:
	letsencrypt/client/client.py
	letsencrypt/client/crypto_util.py