MkOrganization.java:149-154: Implement the "Add team membership"...

The puzzle `1107-31e47c0d` in [`src/main/java/com/jcabi/github/mock/MkOrganization.java`](https://github.com/jcabi/jcabi-github/blob/master/src/main/java/com/jcabi/github/mock/MkOrganization.java) (lines 149-154) has to be resolved: Implement the "Add team membership" API (see https://developer.github.com/v3/orgs/teams/#add-team-membership ) (per https://developer.github.com/v3/orgs/members/#add-a-member , you can't add a user directly to an org; you instead add them to one of that org's teams) and replace uses of this method with uses of that API (or downgrade this method to a convenience method for unit tests).

The puzzle was created by Chris Rebert on 02-Jun-15.

Estimate: 30 minutes, role: IMP.

If you have any technical questions, don't ask me, submit new tickets instead. The task will be "done" when the problem is fixed and the text of the puzzle is _removed_ from the source code. Here is more about [PDD](http://www.yegor256.com/2009/03/04/pdd.html) and
[about me](http://www.yegor256.com/2017/04/05/pdd-in-action.html).