Add special handling for cache TTL < 1 second
Convert log to LTSV
Add comment
Move zero-TTL-skipping logic into MemcachedAccessor
Merge pull request #22 from m3dev/feature/handle-zero-duration-caching



[![LGTM](http://www.lgtm.in/p/SZ1pzab4q)](http://www.lgtm.in/i/SZ1pzab4q)

[:+1:](http://www.lgtm.in/u/SZ1pzab4q) [:-1:](http://www.lgtm.in/r/SZ1pzab4q)