Adding Dockerfile

[kevpie]

Initial effort to build mysql-tarantool-replication replicatord binary.

Mysql source checkout is very very large and performing a shallow clone would be nice but would require libslave referencing an advertised reference such as mysql-src@mysql-5.7.17 may work instead of mysql-src@2303280

Any source or package installation optimizations are beyond my current understanding.

Resulting replicatord is present as /replicatord in centos based Docker image.

Closes #15

[ligurio]

I don't like Docker and prefer to distribute software using packages. But Dockerfile uses CentOS as a base image and we can use it to test build on CentOS additionally to Ubuntu builds on Travis CI (#32).