Replace media module with composer package, fixes T214

Summary:
- add `VENPATH` to point to `vendor/` directory
- update modules config
- reorganize modules config for better search order

Test Plan: Try app.

Reviewers: rjmackay

Reviewed By: rjmackay

Subscribers: dkobia

Maniphest Tasks: T214

Differential Revision: https://phabricator.ushahidi.com/D68