Allow list of packages

[piranna]

Allow to give an optional argument with the desired packages to install and return the full composed install string.

[arve0]

Sounds like a good idea.

[piranna]

Since dependencies packages can have several names on diferent systems, if instead a string or array of strings, it would be used an object where the keys set the OS and/or the installer mechanism and the values the package names of the dependencies for that system. I would check first for the 'npm' entry since we are already using it, so we can install npm packages on demand.