Major refactoring of Repositories.ice (in-progress)

This commit provides a compiling (but not functioning)
refactoring of the ManagedRepository service. Specifically,
a stateful service ("ImportProcess") has been introduced
to manage all of the client interactions throughout an
import.
Working database startup

The ordered/inverse properties on fileset and
its entries were slightly off, preventing server
startup.
Missing managed servant implementations
Properly save Fileset with version info (client/server)

Now the initial upload phase is complete, and its
time to start implementing the secondary activities
which need to be run.
Properly upload files and check sha1

There were several small issues that needed to be
dealt with:

 * "rw" was not being used because of repo.fileById()
 * 0-sized files were not being copied from the client
 * md.update needed only the number of bytes read
WARNING: create MessageDigest during RFS.write()

Rather than necessarily re-parse the file server side,
this calculates the MessageDigest during sequential
calls to write(). If the calls are *not* sequential,
this commit will currently fail with a NPE. Later,
we can re-read the file rather than throw.
Set AppContext on ManagedImageProcessI
Introduce ManagedImportRequestI for actual importing

With this commit, nearly the full import workflow is
implemented, barring returning List<Pixels>.

Blocking at this stage is the getFileByPath() method
in ManagedRepositoryI. It will be necessary to strip
the entirety of the archiving logic in order to move
on.
Strip metadata/companion file processing from import

The setArchive and setScreeningArchive methods were
largely (solely?) handling the linking of original
files to images and plates, etc. Since this will no
longer be happening, all of this infrastructure has
been removed.
Add ImportResponse with List<Pixels>

As a quick fix to have full import working again,
this commit introduces an ImportResponse which
is returned by ImportRequest. Likely the model
will change, so that return values can be linked
directly in the database.
Replace FilesetActivity with Job subclasses

Due to the similarity between "activities" and "jobs",
this commit replaces FAs with various job subclasses,
or perhaps more exactly, with `FilesetJobLinks` to the
subclasses.

Also uses the ome.model.fs package rather than "core".
NB: Add blitz-gc grid target
s/Principal/Ice.Current/ in repo dao after rebase
s/ome/omero/ SecurityViolation in repo dao

Only omero.* exceptions should be thrown from the repository
dao so that the calling class does not have to worry about
any translation.
Properly save Job instances via repo dao

Similar to `InteractiveProcessorI`, a `JobHandle` instance
must be used for saving and modifying jobs to the database.
Remove another metadataOnly flag
Remove unused 'isScreeningDomain'
Move importMetadata to request class
Migrate all server-side ImportLibrary code

Much of the logic that had accumulated in ImportLibrary
was now being called server-side only. To simplify the
call graph (and prepare to provide more cancellation
points), all of this code has been moved server-side,
namely into ManagedImportRequestI.
Change makeDir signature to include `bool parents`

Now, makeDir functions explicitly like `mkdir -p` when
parents is set to true, and like `mkdir` otherwise. This
allows the createTemplateDir method to behave much more
sensibly (though it had bugs of its own).