Make this library easily installable

[s-celles]

Hello,

It will be nice to make this library easily installable with Arduino library manager or PlatformIO

$ platformio lib -g install cbor

It could help to test other library that have cbor as a dependency.

See https://github.com/arduino/Arduino/wiki/Library-Manager-FAQ for Arduino (especially library.properties file)
See for PlatformIO http://docs.platformio.org/en/latest/userguide/lib/cmd_register.html (especially library.json file)

Kind regards