Atomically create all log files and move them into place. #1482
I moved Error class from api_data.py to api_err.py, but it
somehow snuck back in and currently appears in both places.
The one in api_err.py is the correct one, remove the one from
api_data.py.
Merge pull request #1484 from wiredtiger/log-file-create

Atomically create all log files and move them into place. #1482
Return an error if a shared cache configuration is set, but
not enabled.

Check for a configuration via shared_cache=(size=).

Refs #1487
Use none comparison when checking for invalid collator usage.
Merge pull request #1486 from wiredtiger/none-config-2

Some more configuration changes with respect to the "none" value.
Revert default configuration value changes.

They hurt our backward compatibility.
Add support for none configuration string to log compressor.

To be consistent with block compression configuration.
Merge pull request #1488 from wiredtiger/non-config-3

Revert default configuration value changes.
Detect write-write conflicts before no-overwrite cursors decide to skip an update.

refs SERVER-16351
Merge pull request #1489 from wiredtiger/no-overwrite-conflicts

Detect write-write conflicts before no-overwrite cursors decide to skip an update