Handle version and help commands, instead of delegate directly to rails ...

...new

`pah -v` and `pah --version` display:
```
Pah version: 0.0.17
Rails version: 4.1.8
Ruby version: 2.1.5
```

`pah` without args show a help message:
```
Usage: pah <project_name> Creates a new rails application using project_name
       [--version|-v] Prompts the pah, rails and ruby version
```

`pah app` create the app like it does today

cc @maurogeorge @thiagogabriel @rodrigopinto 

Closes #436