OPLOG default settings
OPLOG configuration handling
Refactor for readability and simplicity
OPLOG schema is needed, and it is fixed.

The OPLOG endpoint needs a schema itself because otherwise we would end
up exposing the AUTH_FIELD when User-Restricted-Resource-Access is
enabled.
Change of mind on OPLOG functionality and configuration.

The design so far:

So now the oplog resource is always used to log deleted documents across
API-maintained collections. In time, this will allow to properly handle
If-Modified-Since requests.

However, oplog will also be capable of logging other methods (POST,
PATCH..) Also, the maintainer will be able to make a 'oplog endpoint'
available to clients. This will be a standard API endpoint (can be
configured with auth, url, etc.). Clients might use it to get
a comprehensive list of updates across all API endpoints since their
last visit.
OPLOG implementation
Revert "If-Modified-Since disabled on collection endpoints."

This reverts commit a505abfd96268ac5e7fce00255719cbbb1c7274d.

Conflicts:
	CHANGES
Oplog docs update
Support for OPLOG_NAME and OPLOG_AUDIT.

Also OPLOG now is a boolean which enables/disables the feature, and
OPLOG_ENDPOINT is a string or None.
Merge branch 'develop' into oplog

Conflicts:
	eve/default_settings.py
	eve/tests/config.py
Properly test Oplog IP addresses
Revert "Revert "If-Modified-Since disabled on collection endpoints.""

This reverts commit 36c8cdcfde9fb16db14b296368aa009a0e447594.
Proper If-Modified-Since and If-None-Match examples.
Only log changes on PATCH and PUT methods
Oplog documentation
Merge branch 'oplog' into develop