Adding <space> after ADD command to not to confuse with other non-docker commands

Adding space after ADD to avoid issues with non-docker commands like add-apt-repository.
Otherwise getting exceptions like this - com.kpelykh.docker.client.DockerException: Wrong format on line [ add-apt-repository 'deb http://mirror.jmu.edu/pub/mariadb/repo/5.5/ubuntu precise main' && ]

Cheers!!!