We don't use reverse listing in any of our code, outside of tests, and
it is only exposed through libuplink in the
lib/uplink.(*Project).ListBuckets() API. We also don't know of any users
who might have a need for reverse listing through ListBuckets().
Since one of our prospective pointerdb backends can not support
backwards iteration, and because of the above considerations, we are
going to remove the reverse listing feature.
Change-Id: I8d2a1f33d01ee70b79918d584b8c671f57eef2a0
1. Added KeyValueStore.Iterate for implementing the different List, ListV2 etc. implementations. This allows for more efficient use of memory depending on the situation.
2. Implemented an inmemory teststore for running tests. This should allow to replace MockKeyValueStore in most places.
3. Rewrote tests
4. Pulled out logger from bolt implementation so it can be used for all other storage implementations.
5. Fixed multiple things in bolt and redis implementations.
