Removes start-runtime option

[filipesaraiva]

Removes start-runtime command option. This way, we just need to run pade to start the runtime environment by default.

This change doesn't affect other options except for --help: now the user needs to run pade --help to see the help options, because just run pade start the runtime environment.

Relate to #42.

[lucassm]

@filipesaraiva I think that is a good idea lets the start-runtime command as a default command, when a command is not passed by the user.
But in my view the command start-runtime must exist in order to keep a coherent CLI structure.

[filipesaraiva]

I did some research and the way to remain the cmd function and its CLI structure would be implementing a specific class for default group and add the others CLI function to it. That approach was discussed and also recommended by click authors.

Because the authors discussed that, they created a click-default-group module to be imported and used in projects. The example in module page is very easy to understand.

So, may I use that module?

[filipesaraiva]

I tested click-default-group module and works good.

There are some additional advantages: if you run without argument the script run the --help option; if run with an argument, it starts the runtime environment; this approach also allows both the use of pade without argument and using the start-runtime argument to do the same thing.

[lucassm]

@filipesaraiva I have tested here the modifications and they are working to me, nice!
The pull request has been accepted.
Thanks.