changes after reviews from Breck

Changes based on review comments from Breck
Change for Rahul's feedback
additional commits
Fixed Classify Text use case as per Suraj's comment
NER changes as per Suraj's suggestion
Changes for address stand notebook based on Suraj Comment
base commit for model extension notebooks - ner, classify, seq2seq

Moved changes from master branch to next branch

Author: choudhary-shivani