Update ldaptive to version 2

Grouper is currently using ldaptive v1.2 which is no longer supported. I've created a PR which updates grouper to use the ldaptive v2 API.

https://github.com/Internet2/grouper/pull/209

This PR is targeted at Grouper v5 and shouldn't be merged until it is confirmed working and has been rebased. This initial work includes a temporary snapshot repository so that any ldaptive changes that may be necessary can be quickly pulled in.

These changes compile locally and I've added unit tests to bolster my confidence that the configuration changes work. However, I haven't gotten the integration tests to run locally on my host. I'm happy to work through any issues that are reported on this issue.