Enable multi-select in Tags tree
Run session creation in system context

In an effort to get rid of the periodic failing
tests with:
```
java.lang.IllegalArgumentException: No valid permissions available!
DUMMY permissions are not intended for copying. Make sure that you have
not passed omero.group=-1 for a save without context
```
make all calls to `SessionManagerImpl.createSession` run with an
explicit context for the system group.
ensure that DB enum check is done only once per BF revision
Clean up build.xml: remove cruft, add resources.
Add additional missing classes.
Use getInputs(unwrap=True)
Add use of client.params to test (See gh-2462)

All the metadata associated with a given script context
is contained in the `client.params` object during execution.
Any inspection that needs to happen on what should have or
should not have been passed to the client can be done with it.
Pass servantsPerSession to ServantHolder

The default of 10000 is encoded in both
etc/omero.properties as well as ServantHolder
itself. This makes use of the configurable
property which is passed to SessionManagerI
by BlitzConfiguration.
Fix for most of the broken references

Still a problem with:
MicrobeamManipulation -> Image
Dummy function put in place.

Test with:
components/specification/samples/develop/all-annotated-but-no-link.ome
Merge pull request #2450 from joshmoore/dummy-fix

Run session creation in system context
correct typo in bean name
get root session UUID into managed repository

also tighten constructor exception declaration
add sudo method to public repository
change directory creation to recognize root // user path
document // separator in omero.properties
update copyright header
mirror function signature change in mock test object
fix silly sudo bug
remove username-userid top-directory check
fix bug in creating user-owned directory under root-owned