[#491] Pin every dependency's exact version.

To create these files, I've used pip-dump from the pip-tools package.

All requirements in *-requirements.txt have their versions pinned, and in
setup.py we keep only our direct dependencies and with the versions that
should work (i.e. >=0.11).

We did this so we can guarantee that everyone is using the exact same
version as everybody else, including our deployments.

For more info, check http://nvie.com/posts/pin-your-packages/.
Merge remote-tracking branch 'upstream/master' into 491

Conflicts:
	CONTRIBUTING.rst
	doc/install-from-source.rst
	doc/test.rst
	pip-requirements-test.txt
	pip-requirements.txt
[#491] Add remaining requirements and fix bug in setup.py

There was a typo, extra_requires should have been extras_require.
[#491] Never add CKAN itself to the requirements file
[#491] Ordering requirements files

pip-dump, after adding any new requirement that it finds, sorts it.
As ours were unsorted, it would create noise when you upgraded. I'm
separating that noise in this commit.
Merge remote-tracking branch 'vitorbaptista/491'