Matt Bostock a0201036fa PromQL: Add tests for time/date funcs with arg
Add tests for the date and time functions where an argument is
specified.

Suggested by @grobie:
https://github.com/prometheus/prometheus/pull/1984#issuecomment-246508286

`1136239445` is the reference time used by Go:
https://golang.org/src/time/format.go
2016-09-12 23:12:43 +01:00
..
2016-07-21 00:09:19 +01:00
2016-03-02 23:00:23 +01:00