Dockerized development environment

This commit introduces a fully dockerized dev env you can start on any
machine that has docker without installing any direct OAI dependencies
on host.

This allows to migrate development environments between machines easily.
Several complementary scripts were added to enable smooth transition
between your docker environment and host environment. Your user and sudo
should work inside the environment.

In its current state, the environment can be used to compile
nr-softmodem with 7.2 FHI but it cannot run it due to missing
dependencies.