msisdn - a golang phone number parser

Dependencies:
 - docker
 - docker-compose

How to run the example:
  docker-compose up

Misc:
MNO identifier parsing is not reliable, because I couldn't find a central source
with examples for every country.

JSON-RPC was chosen over default Golang rpc (net/rpc) library since I don't know
the type of clients that will connect to the exposed interface. JSON-RPC seems
suitable because:
 - it also has implementations in python, Java, PHP, ruby, etc.
 - json is human-readable
If I knew the majority of calls came from Golang clients, I'd choose net/rpc and
serve the others via rpc-jsonrpc gateway. I would also consider REST, but that's
not an RPC API.

Data sources:
 - MSISDN https://en.wikipedia.org/wiki/MSISDN
 - NANP https://simple.wikipedia.org/wiki/List_of_North_American_Numbering_Plan_area_codes
 - country dialling codes and ISO 3166-1-alpha-2 https://countrycode.org/
 - MNO identifier lengths https://en.wikipedia.org/wiki/List_of_country_calling_codes