https://jira.hyperledger.org/browse/FAB-1668



Phantom reads problem:
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If a transaction executes a key range query (say key_1 - key_n) leveldb
serves all the keys in the given range in sorted order of keys.
Between simulation and validation of a transaction, some other transaction
may insert one or more keys in this range. Now, this change cannot
be detected by merely checking the versions of the keys present in
the read-set of the transaction.
(though, this check can detect updates and deletes).

A serializable isolation level does not permit phantom reads.

Situations where the phantom reads may not be acceptable:
-----------------------------
 - A chaincode may take a decision based on aggregates of the results of
the range query such as min/max/avg/sum etc. This would be affected
if a new entry gets added to the range query results.

 - A chaincode may want to change all the marbles
owned by a specific user to blue in a tran `t1`. The chaincode may do so
by performing a range query to get all the marbles for the user and
change their color to blue. Now, if a new white marble get added to
the user's assets by an another transaction `t2`,
`t1` should be marked as invalid.

Solution in this change-set:
-----------------------------
For solving this, we can capture the details of the range query
(the query and it's results) during the simulation time and
re-execute the query during validation time and compare the results.
If the results (keys and versions) are still the same,
we can safely commit the transaction.

This changes set introduces
 - Structures for capturing the range query details in rwset
 - Detection of phantom items (insertion/deletion)
   that affect the results of the range query during validation
 - Mark the transactions that are affected by the phantom items
   as invalid to ensure serializability in the presence of range queries

Change-Id: I909841a0234c37795ad7a4ffcca8a9ebd9c9f994
Signed-off-by: manish <manish.sethi@gmail.com>