appengine/search: Introduce SortOptions for search.

Change-Id: Id3f777a0619acacd3906e22132b95f22e3ca585c
appengine/log: Do not send empty offset param

Change-Id: Iee6306dc8550d92881f243054ecfcef43e5be34c
appengine/log: Support retrieving logs for non-default modules.

Change-Id: I11b8e31007fd8036ae9650fa478e876572b5f724
appengine/datastore: allow key filters and sorts on kindless queries.

Change-Id: Ie66de3ac540b42bf39cdf93f60710d49e9c9e448
appengine/memcache: short circuit *Multi calls when the slice is empty

Change-Id: I831173a06bce660c4dd8327260dec7896b6dded4
appengine/search: Support specifying fields and custom expressions.

Change-Id: I52b928f24809474851fc180007f17e8f40105aca
Increase API call allocation acceptable range to [75,85].

Change-Id: Iba0aa2c6134ca15ef74dd222b3a1cc50ffdf199b