Changed primary key for Bag from bagname to auto incremented id column. Relevant changes at all other locations. Fixes #160
Merge branch 'master' into t160_bag_pk_changes
Added default value while creating a new column
Added default value for id column of bagaction table.
Modified test cases for bag pk changes
commented unwanted changes
Merge branch 't160_bag_pk_changes' into travis_postgres_integration