Core Module ec2_elb_lb working on tags

Howdy folks,

Looking at getting into contributing and I think I’ve found (relatively) low hanging fruit that I need to have for a current project - that is setting/modifying tags on ELBs.

Current Github issue for this is: https://github.com/ansible/ansible-modules-core/issues/439

After some investigation this can’t be done through the current version of boto (https://github.com/boto/boto/issues/2549), and using raw SOAP requests to the AWS API would be relatively messy and may need to be changed in the near future as it is gradually being phased out (e.g. EC2 has shut their endpoints down: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/using-soap-api.html )

There is a relatively nice way to do this while keeping the module in Python - but it needs to use boto3 in order to get around this lack of functionality.
This would mean that anyone using the module in the next release would have to install it in order to use the ELB module, which would be slightly inconvenient (in my local version I have a nice message if there’s an import message telling people to install it).

I did look at doing this through botocore, which appears to have it and is lumped in with most installs of boto, however… there is no documentation whatsoever on how to add tags to an ELB, and is not deemed stable quite yet (in it’s current state a new release might break backwards compatibility, breaking this module).

Any thoughts/suggestions/death threats regarding this before I steam ahead with a PR?

All the best,

Ben Doyle