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
Add Trusted-Only:true to the Insight manifest.

See http://docs.oracle.com/javase/6/docs/technotes/guides/jweb/mixed_code.html#trusted_only
Don't sign the webstart jars by default.

We're going to be code-signing in a separate process, so this prevents jars being double-signed, once with the self-signed cert and once with a proper one.

The webstart-sign target is still there, so you can use `./build.py webstart-sign release-webstart`.
Add slf4j dependencies to OMERO.matlab toolbox
Add getOmeroJars() function to list toolbox JAR dependencies

Include a conditional inclusion of the slf4j-api and slf4j-log4j12 JAR files
for versions of MATLAB older than R2011b.
Fix javarmpath() command in unloadOmero()

For some reasons, javaaddpath() supports a cell array while javarmpath()
does not. This commit unifies the behavior by passing the jars as multiple
elements to both functions in loadOmero() and unloadOmero().
remove import logs as annotations on other entities
Apend omero_client to the list of JARs to load
Fix missing variable
Use cellfun to add/remove JARs to the dynamic Java class path

For some unknown reason, javaaddpath(omeroJars{:}) does not work on the CI
node (effectively adding the first JAR only). This commit should fix the behavior by encapsulating the javarmpath/javaddpath calls using cellfun().
fix 11965: join images to plate runs for leaf queries
Adjust version check.
Add an external webstart signing script

Automatically run this script with the existing self-signed certificate as part of the standard docs/hudson/OMERO.sh build
Merge pull request #2211 from knabar/fix-webgateway-missing-var

Fix missing variable (dev_5_0)
Ship log4j.jar with OMERO.matlab and add it conditionally to the Java path

This commit refactors the getOmeroJars() logic to rely on the Java class path
rather on hard-coded versions of MATLAB. The log4j and slf4j dependencies are
assessed independently.
Merge pull request #2226 from jburel/client-server-version

Adjust version check.
Merge pull request #2176 from chris-allan/12097-socket-timeout

dev_5_0: Update upgrade check handling in OMERO.web
Merge pull request #2203 from mtbc/import-log-sql-fix

remove import logs as annotations on other entities (merging for `5.0.1`)