[Tests-only] documentation about running oC10 API tests

[individual-it]

fixes #74

[C0rby]

While trying out to run the tests locally I had the problem that when reva connects to the ldap server with ssl enabled then the Zend framework is returning an error.
It is trying to validate the SSL certificate but since it is a self signed cert it is neither trusted nor signed by any other certificate authority

[butonic]

urgh ... It seems I am blocked by php 7.4 support:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - sensiolabs/behat-page-object-extension v2.3.0 requires php >=7.1.3,<7.4 -> your PHP version (7.4.2) does not satisfy that requirement.
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.0].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.1].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.2].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.3].
    - sensiolabs/behat-page-object-extension v2.3.1 conflicts with guzzlehttp/guzzle[5.3.4].
    - Installation request for sensiolabs/behat-page-object-extension ^2.3 -> satisfiable by sensiolabs/behat-page-object-extension[v2.3.0, v2.3.1].
    - Installation request for guzzlehttp/guzzle ^5.3 -> satisfiable by guzzlehttp/guzzle[5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4].

see owncloud/core#36586

[individual-it]

@C0rby SSL issue should be fixed by owncloud/core#36945