[SPARK-1199][REPL] Remove VALId and use the original import style for defined classes.

This is an alternate solution to #1176.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #1179 from ScrapCodes/SPARK-1199/repl-fix-second-approach and squashes the following commits:

820b34b [Prashant Sharma] Here we generate two kinds of import wrappers based on whether it is a class or not.