initial import of skeleton module
add lists of accepted config keys
add 'cwd' as a config option for processes
fix typo of 'containers_dir' variable
add shared validation for container IDs
fix create_process() arg list
add validation to container-related methods
add port allocation
add writing of container config
initial import of create_proot.py script
clean up 'create_proot.py' script as a more generic PRoot control lib
rename get_container_info() to get_container_config()

get_container_info() may exist later to show additional, live info
move mkdir_p() from proot.py to utils.py
proot.py finds proot executable by default
add utility functions to get user and group names
switch from subprocess to gevent_subprocess
add setup.py
fix syntax error
fix typo