Support iSER driver within the ISCSIDriver flow

This proposes to refactor the current iSER code in order to
avoid code duplication of classes and parameters, and to prevent
instability in the iSER driver flow, for the TGT and LIO cases.

blueprint support-iscsi-driver
Change-Id: Id8b627acf826bfc308d2916852ad5d2f82f8f3d0
Merge "Support iSER driver within the ISCSIDriver flow"