Adding --as-default to CLI omero user joingroup

[kennethgillen]

Adding a parameter to set a user's default group when joining a new group, and a helper function to set the default group for a user.

Ideally the CLI should also allow an ad-hoc "set group" command on it's own, but I see this as an incremental improvement towards that goal, and it certainly answers the use case I have for adding users to a group and setting that to be the default group in one command.

What this PR does

Allows a CLI user to set the default group of a user when adding the user to a group.

Testing this PR

1. required setup

Apply the diff in this PR.

2. actions to perform

Identify a group which your test user does not belong to.

Issue a CLI command with the new --as-default flag like so, with 103 as an example:

omero user joingroup --group-id 103 --as-default

Then issue a further

omero user joingroup --group-id 103

3. expected observations
   Output like the following should appear, if the user was not already a member of the group.

Set the default group of user 793 to group 153

Then

793 is already in group 103

Related reading

Link to cards, tickets, other PRs: https://trello.com/c/sjEk7VQG/487-cli-manage-group-and-user-missing-features

1. background for understanding this PR

2. what this PR assists, fixes, or otherwise affects

The missing ability to set the default group of a user by the CLI.

[joshmoore]

Thanks for this, @kennethgillen. I don't know if I will have time to make a commit today but on top of this I would imagine the following:

• (possibly) use just the first group listed as the default? (as-default becomes set-default)
• a bin/omero group default [--set] $user [$group] method to get/show the default
• python tests

[kennethgillen]

Thanks for the initial review. I don't see a need to rush this into the codebase as is - I'll just use my own branch to do the necessary job to fulfil my own need. To some extent this PR is mainly to add a foundation to build upon.

[jburel]

flake8

./components/tools/OmeroPy/src/omero/cli.py:2270:80: E501 line too long (80 > 79 characters)
./components/tools/OmeroPy/src/omero/cli.py:2271:80: E501 line too long (95 > 79 characters)
./components/tools/OmeroPy/src/omero/plugins/user.py:361:80: E501 line too long (94 > 79 characters)
./components/tools/OmeroPy/src/omero/plugins/user.py:363:80: E501 line too long (91 > 79 characters)
./components/tools/OmeroPy/src/omero/plugins/user.py:367:80: E501 line too long (80 > 79 characters)
./components/tools/OmeroPy/src/omero/plugins/user.py:368:80: E501 line too long (86 > 79 characters)

[joshmoore]

migrated to: ome/omero-py#199