Add per-txn sync configuration support. #1074
Fix a formatting problem with configuration defaults: sub-configurations of the wrong length generated invalid C code.

refs #1074
Split the global transaction_sync configuration into two parts: a sync method (dsync, fsync or none), and a sync_on_commit flag (false by default).  Convert the transaction-local configuration into a simple boolean "sync" using the configured method.

#1074
Minor cleanup.  Add enabled/none test case back in. #1074
Clarify that the transaction sync setting overrides the global setting.  Add some upgrading documentation.
Merge pull request #1076 from wiredtiger/txn-sync

Add per-txn sync configuration support. #1074