Change play instrumentation name to play-mvc and restructure dirs

[breedx-splk]

This is part of #4952

play renamed to play-mvc, and play-2.4 to play-mvc-2.4 (and same for 2.6).

Final structure looks like:

play/
  +---- play-mvc/
  |         +----- play-mvc-2.4/
  |         +----- play-mvc-2.6/
  |
  +---- play-ws/
            +----- play-ws-common/
            +----- play-ws-1.0/
            +----- play-ws-2.0/
            +----- play-ws-2.1/

I didn't change the actual instrumentation name, though. I didn't think we'd want that (would impact users who have chosen to disable it?)

[trask]

I didn't change the actual instrumentation name, though. I didn't think we'd want that (would impact users who have chosen to disable it?)

go ahead, we've still been changing the instrumentation names to match when we change the module names, and we doc it in the migration notes at the top of the release notes

[trask]

thx @breedx-splk!