added guide to install from source code

[beenotung]

for this issue: #1302

[blurHY]

This can help newbie users.One-click to install&run zeronet

[HelloZeroNet]

I think if it's not super complicated, then it's better to not hide these commands inside an install script, but let the user know whats the actual steps, so they can decide if they only install it to local user, system-wide, what command they want to use (py, python, python2, pip, pip2)

[blurHY]

Newbies may don't know what python is.
They just want to start using zeronet as quickly as possible.
We should attract new users by making it easier to use.
Install script and step-by-step tutorial are both needed.
It's not a priority yet,but you can merge this i think.

[HelloZeroNet]

For newbies I would recommend to use the bundle package as it does not need anything to do, just unpack and run.