https://jira.hyperledger.org/browse/FAB-1664



This changeset:
- Renames package ledger/util/db to ledger/util/leveldbhelper
- Implements a leveldb provider
  (that enables using same leveldb instance as a multiple logical dbs)
  in util package for being able to reuse across statedb, index,
  and later for historydb
- Implements a provider as a single point of invocation
  for managing multiple block storage
- Uses a single leveldb instance for block storage index
- Makes the structures other than providers as private
  to their respective packages

Change-Id: I5f0b3b9aa8ef3ac1ccdce4f3c6fa6d842b5318c1
Signed-off-by: manish <manish.sethi@gmail.com>

When chaincode is deployed, it fills the peer debug log with
many megabytes of binary dumps, making it difficult to
troubleshoot through the noise.

Change-Id: I7be1814632f0fda272b10793e7e6413b7d1de0e4
Signed-off-by: denyeart <enyeart@us.ibm.com>

FAB-1505 refactors CouchDB code to be aligned with LevelDB structure.
FAB-1337 applies all ledger tests written for LevelDB against CouchDB.

In order to test the CouchDB refactor,
had to implement FAB-1337 in same changeset to test.

Like most refactors, this changeset touches a lot of files and code,
since it is not feasible to do a partial refactor.

Tests related to versioning and deleting have been commented out,
these will be re-enabled in subsequent changeset when CouchDB
has the support, in order to keep this changeset size more reasonable.

Change-Id: I0d2d6cca89bd0252f6e84317457a9140b3a0d7a5
Signed-off-by: denyeart <enyeart@us.ibm.com>

https://jira.hyperledger.org/browse/FAB-1543



Change-Id: Ib11d1a2fc14cf81dd5380eadf93e73e1c56113e3
Signed-off-by: manish <manish.sethi@gmail.com>

https://jira.hyperledger.org/browse/FAB-602



The refactoring allows sharing of transaction execution and validation code across goleveldb and couchdb.
This refactoring also allows plugging-in different schemes for various aspects of transaction execution
such as maintianing isolation during simulation, validation and commit.

Change-Id: I0d3fb1cdff99c3f6f991e7b7469920173f194a87
Signed-off-by: manish <manish.sethi@gmail.com>