Adhoc: Remove the Initialize method from the DataEntityDataReader.

[mikependon]

As part of the fixes made to the #668, the Initialize() method within the DataEntityDataReader class seems to be not important anymore (and has been invalidated).

With the fix we introduced on the mentioned issue, we tend to eliminate the logic that filters the list of the DB Fields if being compared to the fields of the Data Entity as it is really possible that they are not equal, but the users/callers can still pass the list of mappable fields via mappings attribute.

Many thanks to @SpaceOgre for pushing and letting us realized this.