New option to disable user creation via web
Add documentation for new config option
Fix docs, remove deprecated comment
[1262] basic image upload functionality
[#1262] fix how url field is handled
[1262] use logic instead of requests
[#1262] fix test failures
Don't exempt sysadmins
[#1226] Add tests
Merge branch 'master' into 1226-user-create-option

Conflicts:
	ckan/logic/auth/create.py
	ckan/templates/header.html
[#1226] Return the old behaviour for create_user
[#1261] add filesize limit, make storage folder backwards compatable, document a bit more
[#1262] First working version of the JS module for image uploading
[#1262] Adds in doc blocks into the image_upload JS module
[#1262] Adds support for different field names for image upload
[#766] Stop Travis build if a dependency install fails

To do so, I needed to split our ./bin/travis-build in two files, one with the
deps install, and one with the test run. Doing so allows me to use the
"install" directive in Travis, and break the build as soon as something fails
with it.
[#766] Remove redundant datastore_test psql user creation
[#1262] make tests pass
[#1155] Document how to upgrade the dependencies
[#766] Move solr configuration to travis-run-tests

I was unable to run Jetty-Solr's configuration on travis-install-dependencies.
Probably something to do with Bash's "set -e", but I was unable to pinpoint
exactly, so I left it into travis-run-tests. No big deal.