Remove "first_id" from the page modify structure.  This should have been removed when transaction IDs were switched to 64 bits.
refs #553
Remove the 'transactional' keyword, we're always transactional.
The 'transactional' keyword is gone, remove uses of the
WT_CONN_TRANSACTIONAL flag.
Now the 'transactional' keyword is gone, remove uses it in the test suite.
Add a separate thread to migrate cache data into the primary (it's a
separate thread because it's possible to copy data out of the cache
without acquiring a lock, so there should be a reasonable amount of
overlap).

Fix a bug in the cache vs. primary comparison code, we were comparing
the value, not the key.

The WT_EXTENSION_API.transaction_oldest method doesn't require a
WT_SESSION handle, simplify it.

Minor re-ordering of the shared library load/unload code to simplify
error handling.
Merge branch 'develop' into memrata