Added license in docker/docker.cpp.
Added docker_tests to test the docker abstraction.
Added docker::killAndRm() to performs 'docker kill && docker rm (-f)'

This will be faster than doing 'docker rm -f' on a running container.
Refactored docker::ps(), added 'prefix' option to inspect only interested containers.
Moved cpu/mem constants from cpushare.cpp/mem.cpp to cpushare.hpp/mem.hpp
Refactored docker::usage() and docker::run().

Support resources restriction in docker::run().
Support resources display in docker::usage().
Also fixed docker::usage() to check for destroying containers
before calling docker::inspect().
Added a DockerContainerizer::recover test.
Docker update