Beta: Update cxserver to use Apertium service

Changes:
1. Use apertium-beta.wmflabs.org for mt.apertium service
2. Added registry in config.erb
3. apertium-* packages are no longer needed. Apertium is used as service.

Depends on: Ie071199078ce40f9a3f3e25e2e58430330328087

Change-Id: I94597e7e78e97c4b34e3ad40c32a6ca97afeccfa
Merge "Beta: Update cxserver to use Apertium service" into production