Add a mixin for marking deprecated modules

* This mixin standardizes the previously ad-hoc deprecation warnings on
  modules that have been moved.

* Uses the mixin in 3 existing modules that already have (or should have
  had) deprecation warnings.
Remove stupid debugging load()
Remove $
Merge branch 'feature/deprecated-module-mixin' of github.com:jlee-r7/metasploit-framework into jlee-r7-feature/deprecated-module-mixin