Epic: write a configurator script to ask for the parameters to install

Starting from scratch create an interactive configuration tool
asking for all the required parameters to setup
- [ ] in docker (first)
- [ ] in a single server (second step)
- [ ] in the various cloud providers (third step)

So you can install OpenServerless with:

- ops configure
- ops install

in all the environments

and create the documentation for all of this.

Related issues:
#60 Task-util-config: add a custom label to show to the user - MERGED
#61 Task-util-config: it should be possible to set a default value for a parameter that depends only on the current parameter - MERGED
#62 Task-util-config: it should be possible to set a default value for a parameter that depends on one or more parameters different from current value - OPEN
#69 Task-util-config: allow digits in the name of the configuration keys - MERGED
#70 Task-util-config: have a better error message if the configuration file is not present. - OPEN