Set default socket timeout correctly (Fixes #12097)

Python socket timeouts are specified in seconds as floating point.  This
commit sets the default timeout to a more reasonable 3 seconds, allows
the specification of a floating point timeout value, removes the
assumption that the timeout is specified in milliseconds and documents
all of the aforementioned.
Support for configuring the upgrade check URL (See #12097)

This commit adds configurability to the upgrade check URL via the
OMERO.web configuration mechanism.  Upgrade checks in OMERO.web can now
be disabled by running:

    bin/omero config set omero.web.upgrades_url ''
Use existing "omero.upgrades.url" configuration option
Bugfix: Weird behaviour after switching users

After switching user new service adapater instances were created but never
passed on to the registry.
Updated copyright date
jquery-ui custom images cleanup
add media type for import logs

omitting x- prefix for http://tools.ietf.org/html/bcp178
adjust how the import log is created and linked to the fileset
add upgrade script to fix old import logs

to repeat in OMERO5.0__1 for those already on OMERO5.0__0
add import log find method to the metadata service
adjust import library to use new log finding method

Conflicts:
	components/blitz/src/ome/formats/importer/ImportLibrary.java
add integration testing for new metadata service method
Load log files using new method and not file annotation.
Fix copyright and space.
permit empty lists of images to be queried for import logs
include import log in fileset graph traversal
add new SQL DOMAIN types
adjust Java DSL code to use new SQL DOMAIN types
fix definition of sizes to match model
update patch number and upgrade scripts