Integration Test docs don't specify how to run integration tests

[oscardssmith]

This is a really simple thing, but it should be added.

[pdurbin]

@oscardssmith good catch. The file to edit is doc/sphinx-guides/source/developers/testing.rst

[pdurbin]

As I've been reporting at http://irclog.iq.harvard.edu/dataverse/2018-07-02 the API test suite doesn't "just work" on a fresh clone of the git repo. I'm seeing the following errors:

• cp: directory ../../conf/docker-aio/dv/install does not exist
• cp: cannot stat 'pgdriver/postgresql-8.4-703.jdbc4.jar': No such file or directory

[pdurbin]

I just created pull request #4801 and will drag this issue to code review at https://waffle.io/IQSS/dataverse