pkg/search: add modtime in WANT to fix tests

Also fixed fakeindex clock to use a time.Time.
And synchronized the fakeindex and the indextests clocks to the
same origin.

Change-Id: I986abca300d61241069132619028f470cacd61da
Merge "pkg/search: add modtime in WANT to fix tests"
search/index: invert depedency. search now depends on index.

creates new package types/camtypes for misc types needed by both. might eventually go away as
search matures.

Change-Id: Ib771ead7bea39936ba478b7e5d58de997060861b