travis: Disable docker as this is breaking the travis build
travis: Disable docker as this is breaking the travis build

This reverts commit 91955ca7bec90265237d361c6b4c987e3f3e242d, reversing
changes made to 95c73d157c7d83a7ec7eadab37e70a54efab7d64.

Travis-ci is breaking when combining installing apt-get packages and
having the sudo service. Thet apt-get waits for a y/n and it is not
answered by the platform.

This is tracked as https://github.com/travis-ci/travis-ci/issues/5622

zecke/osmo-smsc,woglinde/osmo-smsc,woglinde/osmo-smsc,zecke/osmo-smsc,woglinde/osmo-smsc,zecke/osmo-smsc