Add Octokit::Client::Apps#find_user_installations method

[greysteil]

Specs will fail as I haven't added a cassette. Can someone who already has the required environment variable set up do so?

[coveralls]

Coverage increased (+0.0004%) to 99.274% when pulling 5aed8a4 on greysteil:add-find-user-installations into c3aa3e0 on octokit:master.

[greysteil]

@tarebyte - any chance you could do me the honour of a cassette?

[coveralls]

Coverage increased (+0.002%) to 99.276% when pulling 3eb5b17 on greysteil:add-find-user-installations into c3aa3e0 on octokit:master.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling cd212f7 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling adbd332 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling adbd332 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling adbd332 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling adbd332 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[greysteil]

Now with passing cassette (I cheated, and borrowed the one for find_app_installations which has an identical response).

Bumped the Ruby 2.4 version on travis as I was getting segfaults on 2.4.0.

[coveralls]

Coverage increased (+0.0003%) to 99.276% when pulling c778ea2 on greysteil:add-find-user-installations into 0f13944 on octokit:master.

[greysteil]

🎉