Deflake memcache unit test.

It also runs 3x faster now in the happy path.
Remove Sleep() from ThrottledLogger test and check output format.
Merge pull request #122 from youtube/deflake-memcache

Deflake memcache unit test.
Merge pull request #123 from youtube/deflake-logutil

Remove Sleep() from ThrottledLogger test and check output format.
Merge pull request #114 from youtube/replication

Replication
Merge branch 'master' into replication