Initial fs.py plugin

Only available command at this point is `repos`, which prints
all the repositories available. The classification as `Managed`,
`Script`, or `Public` needs refinement.

`--managed` filtering is enabled. A ranking of the individual
managed repos needs to be introduced, via stars or similar.
Add `repos` command to fs.py

Minimal listing of filesets (by-age) with some
filtering based on the transfer mechanism used.
Generic transfer filtering mechanism

Now all the `--with-transfer` arguments passed to `sets`
are OR'd together to choose which filesets will be listed.

The map of symbolic names to transfer classes from
`AbstractFileTransfer.java` is used to provide simpler
arguments (e.g. `--with-transfer=ln`) though the full
class names can be used as well.
Fix minor compile errors in fs.py
Add styles from text.py to fs.py
Deprecate hql --admin in favor of --all
@admin_only decorator in cli.py

Adding @admin_only to any regular pluin action method will
cause a check against `EventContext.isAdmin` to be made
before execution begins.

The expected signature is:
```
    from omero.cli import admin_only

    @admin_only
    def method(self, args, ...):
        ...
```
Remove old comment re: loadplugins
Add 'checksum' support to RawAccessRequestI
Initial --check implementation for 'fs sets'
Minor cleanups to RawFileAccessI
Refactor limit/offset into cli.py
Add submit/waitOnCmd to omero.client

This refactors the method from omero.gateway
into omero.client for general usage. The additional
`client.submit()` takes all the same options as
`waitOnCmd` and also creates the callback object.

The exception handling still needs to be decided.
Working checksum check

The only limitation here is that the check is performed
on the assumed only managed repository. As soon as there
are multiple reponsitories, this will break down.
Add image count and filtering to fs.py
Fix '--with-transfer' login
Strip out TODO block
Introduce omero.CmdError for waitOnCmd

This removes the dangling '???' regarding what type
of exception should be thrown. `CmdError.err` provides
access to the original error object (and is required).
Improve ordering options
fs.py: Add `fs archived` command

This command provides a listing of archived original
images. This should allow users to detect potential
migration candidates.