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: I19205a9bd60c0fab513703f46630d292631c72ac
Addresses: blueprint rubocop-integer