Add license.
Implement command to lock a repo to avoid push.

First implementation attempts by copy the `lock` command
and addapt it.

Already done:
  - adjust the usage text
  - adjust the opts dispatching
  - introduce constants
  - remove unnecessary functions/code
  - rename functions
Adjust thefunctions.
Fix the usage text.
Fix variabloe name.
Fix variable name.
Fix variable name.
Add VREF file for locking repos.
Fix variable name in declaration.
Fix var access.
Extend the message and exit with non zero.
Format the time stamp.
Use international style date.
Remove clutter from reject message.
Use die instead of exit.
Fix unitialized var warning if -m is omitted.
Fix syntax error due to wrong comment chars.
Remove unnecessary variable.
Delimit user name so i see if it is empty.
Use Getopt::Long for the options stuff.