Remove support for Gerrit over ssh

From now only the REST API is supported.

This makes installation of the package a bit lighter as we no
longer depend on paramiko and pycrypto

Change-Id: Ieda773d596fd43047c05895f3304690ddf709094
Stop using pylint

- It has dependencies on several other modules.

- It is too strict.  It should be enough to run pyflakes.

Change-Id: I17d1c3390e5530e2b2a86d680d9816a29f272707
Migrate setup to pbr

pbr provides better version handling, and automates the release
notes and list of authors.  This means we have to spend less time
manually updating things.

Change-Id: Ie79d706ec7a177f437b6bb0e38a9bded8bc4bb9e
Set HTTP headers to reduce data transfer time

Request compact JSON by setting:

  'Accept: application/json'

Request compressed response by setting:

  'Accept-Encoding: gzip'

Change-Id: Ie1b5169d43b164f0e06aa765cbf76cca25d629f3
Set Content-Type header on PUT and POST requests

The Content-Type must be set to "application/json" for PUT and
POST requests.

Change-Id: I859e6cb18b981935b1788a943ec195955fb1e46d
Include full description in the setup config

This was missed in the migration to pbr.

Change-Id: Idb4167e99a02a8909fe152956a083fe133f1fc86
Upgdade requests to 2.2.1

Change-Id: I2ff6b5fcd4460ceaa4db9dcde6832719f2557c7e
Update the README

- Rewrite introduction
- Rename "REST API" section to "Usage" and add summary of example
- Mention dependency on the requests library
- Switch order of "Installation" and "Prerequisites" sections
- Mention removal of ssh support

Change-Id: Iebf015e554a0de751abeba0f5394ed59f32585d5
Revert "Remove support for Gerrit over ssh"

The ssh interface is still being used and patches are being
contributed [1].

It's easier to revert the removal on master than attempt to keep
the support in a separate branch.

This reverts commit f0b77968389966cd7bad0cac1fe7f04526eafde1.

[1] https://github.com/sonyxperiadev/pygerrit/pull/21

Conflicts:
	README.rst
	example.py
	requirements.txt
	setup.py
	unittests.py

Change-Id: I9e02208c57cb2022ff39cff6650101ed40c0519d
Upgrade paramiko to 1.14.0

Upgrading to a later version that includes better support for proxies.

This introduces an additional dependency on the ecdsa cryptographic
signature library.

Change-Id: I5971296ab2d9789612a6f28c72559c86a25796a0
Add support for ProxyCommand in GerritSSHClient

Change-Id: I776a58b2cdac17e3eafc985ee727cd88e8294ccc