Handle DB.tx better

[vaibhavchellani]

Right now we create a DB clone and generate a database transaction for per tx state updates, we rollback the state updates if the processTx turns out to be invalid.

We return the DB clone that was used to generate DB.Tx to another function so that it can rollback tx incase of invalid tx.

We want to find out a better way to do the above, while the current way works its extremely smelly