Revert "added functionality to use first part of email as usetr_nicename for users with no screen name to fix issue with author link breaking."

This reverts commit 09bbcec7af295983101f57e168fbac40cbd27920.
Reverting the revert.

This reverts commit 5422b58187939cdd3734370443a5d643c0bbfb58.
integrated Epsilon register functionality for SSO registration