Add Connection-Type, Domain, and ISP databases

An enum was no used for the Connection Types as Json.NET doesn't support
setting invalid enum values to null (at least without a custom
deserializer), and we may wish to add new field values in the future
without breaking previously released code.
Updated ISP tests.
Removed dated comment
Merge pull request #9 from maxmind/greg/new-dbs

Greg/new dbs