Add get subcommand to CLI obj command (rebased)

[ximenesuk]

See gh-4071

--rebased-from #4071

[mtbc]

https://ci.openmicroscopy.org/job/OMERO-DEV-merge-integration-python/lastCompletedBuild/testReport/OmeroPy.test.integration.clitest.test_obj/TestObj/ passes nicely.

[mtbc]

(Testing instructions seem a little light but ...) I'm puzzled:

$ omero obj get UploadJob:17 finished
Using session 9923d6ef-7b44-4fea-9898-82ebc5469770 (user-2@localhost:4064). Idle timeout: 10 min. Current group: private-1
No object found: UploadJob:17
$ omero hql 'select finished from UploadJob where id = 17'
Using session 9923d6ef-7b44-4fea-9898-82ebc5469770 (user-2@localhost:4064). Idle timeout: 10 min. Current group: private-1
 # | Col1                     
---+--------------------------
 0 | Tue Sep  8 10:15:53 2015 
(1 row)

Are timestamps too complex a type? The "No object found" suggests the problem isn't with the actual field.

[mtbc]

(Some experimentation suggests that dimensioned properties aren't yet in scope for this, that's okay.)

[mtbc]

For really basic properties on the best-known object types this PR does seem to be working fine.

[ximenesuk]

Thanks @mtbc. The limit of get in this PR is basic properties, anything more complex is for discussion and scoping later.

The obj command uses the API rather than hql, that may account the No object found message.

[mtbc]

HQL uses the API too ... ? But if all this is expected then, especially as this is a rebase, good to merge. (Not sure if some RFE is needed re. "no object found" wrongly suggesting there isn't such an object available in the current context? But not this PR's fault I think.)

[ximenesuk]

Sorry, I meant that it uses the query service get method rather than forming its own hql. Might that have a different effect at the server end? /cc @joshmoore

The No object found message is certainly consistent with the same exception being raised by other commands, e.g. update - though it might not be completely helpful :-)

[joshmoore]

I don't know why get would show nothing. It seems like a problem to dig into elsewhere. 👍