This change set adds Append() to the consenter support,
and changes the eviction logic to use Append() instead
of WriteBlock, so that the blocks that are pulled from OSNs
are not changed and are written as is into the ledger.

Change-Id: I76abe64990f1855b53dadb0655c5830169ef7ed1
Signed-off-by: yacovm <yacovm@il.ibm.com>