GitLab

Execs top-level commands but doesn't roll back correctly

Aims:
- cleaner cli load-point code
- move more argument logic to argument module
- move command loading to the seperate service cli modules:
    each command spec module will provide a mechanism for loading
    command interfaces (all of them or specific cmds)

FEATURE: subcommands of a callable command are not allowed. e.g.:

if the following exist as callable commands:
cmd1_cmd2
cmd1_cmd2_cmd3

then cmd1_cmd2 is resolved, but cmd1_cmd2_cmd3 is not

UNFIXED: There is still a case of syntax-error or --help call where the best
possible help message is not resolved:

cmd1_cmd2_cmd3 where cmd1_cmd2 is not a command

gevent depedency is not needed after that