Client libs links to packages in pypi and npm

[sambarza]

Added links to client lib packages published in pypi and npm.

Close first step of #21

[nicola-corbellini]

What do you think about joining the two in a single file? Hence, we write the stuff only once and for code snippets we can use tabs

[pieroit]

I'd go for seprate pages, so we can have a small hello world and maybe link to external friend projects using the lib