Generate downstream in interactive txn coord
clocksi_vnode update matereializer after transaction commits
Merge branch 'master' into downstreamop
Fixed bug: always use vec_snapshot when generateing downstream op
Merge with master
Merge branch 'master' into downstreamop
Fix bug: remove calling to floppy_rep_vnode and floppy_coord_sup
Merge branch 'master' into downstreamop
Fix a bug: tx_coord did not send downstream op to clocksi_vnode
Add downstream generation to stx transaction
Add a failing test
Append downstream ops in clocksi_vnode instead of in tx_coord
Merge with master
clocksi read returns snapshot state instead of value
Fix concurrent transactions test
read proper snapshot for downstreamop generation
Merge branch 'downstreamop'

Conflicts:
	src/clocksi_interactive_tx_coord_fsm.erl
	src/clocksi_tx_coord_fsm.erl
	src/vectorclock.erl
remove redundant downstreamset, fix logrecord structure when writing downstreamops to log
Add dcid to commitrecord
add reader for reading transactions in commit-time order from a partition's log.