[#1188] Allow organization dropdown to be displayed

The current logic was unclear. If a user belongs to at least one
organization, the dropdown will be displayed, both on the created and
edit forms. Same for the visibility one.
[#1188] Allow empty orgs if datasets can be unowned

If the "create_unowned_dataset" is set to True and you are not a
sysadmin and select the "No organization" option on the dataset form,
you get a validation error.
Removed limit of number of arguments passed to ``user add`` command.

This is needed as the ``user add`` command is supposed to accept a variable number
of arguments.
[#1022] Fix cross-references in API docstrings

Use :py:func:, :py:class: etc to do proper hyperlinked cross-references.

Also a few other minor docstrings formatting fixes.
[#1380] Encourage installing latest release in source install docs

Needed an automated way to get the latest version number, so I added
functions to doc/conf.py for this, and then used them in the source and
package install docs.
[#1380] Remove hardcoded filename
Merge branch 'master' into 1188-fix-org-list-dataset-form
Revert "[#1188] Allow organization dropdown to be displayed"

There is certain logic, albeit a bit flacky, in hiding the organization
dropwdown, in that if shown, any user belonging to an organization could
take ownership of any unowned dataset in the instance. We need to
properly define the auth rules and enforce them at the validator level
as well. For the time being, showing the dropdown only to sysadmins
makes sense (and of course fixing the original bug on the visibility
field validator, which is done on the next commit)

This reverts commit f366ba684340adbb903b78bc5beb871069a6a0c2.
[#1188] Fix visibility validator

To not rely on owner_org being present, when the validator gets a value
of private and there is no owner_org, we request the dataset anyway and
check if it actually has an owner_org.

Added new validation tests
[#1188] Remove debugger call
[#1380] Fix some broken hyperlinks in the docs

Stop Sphinx from hyperlinking part of the URL in pip install commands.
[#1188] PEP8 fixes
[#1392] Fixes member add page within groups
Fix test failures associted with related_list

The related_list dictization changes returned them as returned by
the database. This change gives it a default order if they're not
previously sorted.
[#1398] Adds: 'word-break: break-word;' for better word breaking on long words
[#1302] Removes mentions of 'no description' from templates
[#1360] Update package_update docstring.
Merge branch '1022-api-docs-improvements'
[#1422] More secure default for the repoze secret key

The who.ini file has a secret key used during authentication. To make sure
users don't forget to update it we can use the beaker session secret which
is generated randomly when creating the ckan ini file.

If users define a secret in the who.ini file, this one will be used.

To do this, we use a small custom plugin that checks the secret key and
calls the core repoze plugin afterwards.
[#1425] Call logic.NotFound