Compatibility with dnspython 2.0

[ianhelle]

I've created a PR with a simple change that uses either Resolver().resolve() or Resolver().query() depending on which version of dnspython is installed. #302
Tested with both versions. I get test failures with TestNet.test_get_http_json but this seems to be unconnected with net.py code and failed before I made any changes and happens with either version of dnspython.

Haven't made any entry in the change log since there's already a note in there about fixing dnspython deprecation warnings.

[fseesink]

I'm curious where this is at. I just started testing ipwhois, and it seems to work just fine with dnspython v2.0.0, at least with Python3. So not sure why the module's requirements are set to dnspython<=2.0.0 (I'd think if there's an issue b/w v1 and v2, it would've been written dnspython<2.

Current dnspython is 2.1.0. And as part of a devops team working on a project where we're already using the latest dnspython, trying to install ipwhois causes dnspython 2.1.0 to get uninstalled and 2.0.0 to be installed.

[ianhelle]

This is the issue that I was trying to address in #302. If dnspython is installed first pip (depending on version) issues a warning or fails because of the <=2.0.0 requirement. The dnspython interface changed but not (as far as I can see) the basic functionality. The structure of the returned data from resolver.query() changes in post v2.0.0 resolver.resolve() but I can't see that this affects ipwhois functionality.

[secynic]

I think I will be dropping python 2 support. I updated requirements to latest for dnspython in dev branch. Will think about this some more before closing.