Add elasticsearch 5.x support

[aamatte]

Changes:

• Query size can't be 0 anymore. It was changed to 10000.
• Fix rollover.
• Use types text (instead of string) and keyword (instead of string with not_analyzed).
• Updated queries tests. I'm not sure if the changes made are correct.
• Changed time zone string format

I'm not sure if there are more changes to be made, or if the test changes are representing the expected behaviour.

All tests are passing with elasticsearch@5.6.