* create votes table and indexes
* initial db call rewrite
* setup votes table in tests
* rewrite election status
* update api tests
* update tests
* bigchaindb set-shards should change 'votes' table too
* Forgot to add change to bigchain.py in last commit
* update test
* move exceptions
* collapse line
* revise test
* remove obsolete test
* remove votelist from blocks
* sharding and replication
* documentation changes
* language change
* more readable assertions
* fix exception
* test exceptions
* remove parameter
* remove loop
* Test Bigchain.get_blocks_status_containing_tx()
exception case
* Test Bigchaindb.has_previous_vote()
* Add missing blank lines (pep 8)
* Group imports
* Move ImproperVoteError into .exceptions.py
* Simplify logic
* Simplify formatting
* Imrpove the docstrings a bit
* Move GenesisBlockAlreadyExistsError
into .exceptions.py
* Remove unused import
* Add missing blank line
* Remove extra blank line
* Group imports from same module together
* Add test for Bigchain.transaction_exists()
