First draft of the web interface

Send a JSON description of a (single) source location
Test server, receiving the web interface JSON

Relies on cpp-netlib + jsoncpp
Cleanups in ledstrip + support for set(array<Color>)
missing const
Connect pieces together (nothing useful yet, however)

- generate an executable 'table' that listen on port 8000
- creates a table with 97 LEDs and compute their locations
- print on the console the JSON commands received