Improve docs for UnaryExpression.
Initial implementation of pagination for older Sqlserver

Old SQLServer does not support anything like LIMIT/OFFSET. Instead we
have to use a subquery workaround.
Add additional tests for pagination + conditions.
Fix additional failing tests under old SQLServer

The query transformation process requires decorators to be applied to
the original results when replacing the query with a copy as the
original query is what the end developer has access to.
Fix error in old SQLSserver.

Identity columns must be undefined.
Skip wincache tests if wincache.enablecli is off.

If wincache is disabled, skip the tests.
Merge pull request #3371 from cakephp/sqlserver-pagination

3.0 - Fix pagination in Sqlserver2008