Merge pull request #1812 from sbesson/homebrew_insntallation

Fix URL for Homebrew install in the hudson shell script
Merge pull request #1792 from knabar/feature-omero-config-set-from-file

develop: Add feature to load value for an individual setting from a file
Refactor CLI prefs unit tests to use pytests capsys fixture

- Drop MockCLI to use CLI instance itself
- Use capsys to systematically check the sys.stdout and the sys.stderr
Fix flake8 for the clitest unit tests
Add test/unit/clitest to the directories to flake8 in .travis.yml
Use absolutepath for setuptools in setup.py
Clean up code.
Remove tabs and whitespace.
Worked around method_decorator problem with custom getattr
Add cleanup() methods to test_hdfstorage.py
Add check if all required fields are entered.
adding support for FORCE_SCRIPT_NAME in nginx config
Update URL in Edit_Descriptions.py example
Add check and remove tab/whitespace.
refactoring SendFeedback class and adding HTTP_USER_AGENT

to the feedback sent from omeroweb
making QA port configurable
removing whitespace (@sbesson request)
Do not allow to remove guest from Guest group.
Do not allow to move guest from Guest group using DnD.
Initialize table before file chooser.