Disable the NumericLiterals cop for rubocop

- Disable the NumericLiterals cop in the .rubocop.yml file - this cop enforces
  an underscore '_' every 3 characters of an integer. This doesn't make much
  sense in our use case and reduces readability. Especially for port numbers.

Change-Id: I32617941e3ee1f43e06fb5b9017e6ccab0cf5050
Addresses: blueprint rubocop-integer