Switch CLI API dispatch framework to `docopt_dispatch` about git-repo HOT 2 OPEN

Any docopt-alike implementation is very fast for development, but it has limitations that can't be fixed:
You can't allow to implement addiotional commands/options. This will block plugin author from adding service-specific commands (i.e. for service with locally-accessible repositories something like git --git-dir=/home/git/gogs-repositories/user/repo.git remote ...).

from git-repo.

well, this is a more global design issue, and this discussion better fits in #28 …

This issue is only there as a reminder to replace my custom command "dispatch" with docopt_dispatch, because I basically reinvented the wheel without knowing.

from git-repo.