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.
* adds netstate rpc server pagination, mocks pagination in test/util.go
* updates ns client example, combines ns client and server test to netstate_test, adds pagination to bolt client
* better organizes netstate test calls
* wip breaking netstate test into smaller tests
* wip modularizing netstate tests
* adds some test panics
* wip netstate test attempts
* testing bug in netstate TestDeleteAuth
* wip fixes global variable problem, still issues with list
* wip fixes get request params and args
* fixes bug in path when using MakePointers helper fn
* updates mockdb list func, adds test, changes Limit to int
* fixes merge conflicts
* fixes broken tests from merge
* remove unnecessary PointerEntry struct
* removes error when Get returns nil value from boltdb
* breaks boltdb client tests into smaller tests
* renames AssertNoErr test helper to HandleErr
* adds StartingKey and Limit parameters to redis list func, adds beginning of redis tests
* adds helper func for mockdb List function
* if no starting key provided for netstate List, the first value in storage will be used
* adds basic pagination for redis List function, adds tests
* adds list limit to call in overlay/server.go
* streamlines/fixes some nits from review
* removes use of obsolete EncryptedUnencryptedSize
* uses MockKeyValueStore instead of redis instance in redis client test
* changes test to expect nil returned for getting missing key
* remove error from `KeyValueStore#Get`
* fix bolt test
* Merge pull request #1 from bryanchriswhite/nat-pagination
remove error from `KeyValueStore#Get`
* adds Get returning error back to KeyValueStore interface and affected clients
* trying to appease travis: returns errors in Get calls in overlay/cache and cache_test
* handles redis get error when no key found
