Forgot Password Feature

We have been experimenting and using mean as a starting point for JS applications. Thought it was high time to contribute back. :-)

Updated it to meet the latest version of MEAN.... Please review the code, and we will try and incorporate your feedback and suggestions.
@pratik60 Upon further review, I'm not convinced that this belongs in the `config` file. Any reason why this function couldn't live in `packages/users/server/controllers/users.js`? Do you foresee developers needing to customize this function regularly?