* set up leveldb-datastore
* Adds test for leveldb
* pulls in nim-leveldb by url and hash
* Fixes basic tests for leveldbds
* Implements query iterator
* Fixes include path for defaultImpl
* Review comments by Tomasz
* adding monted store
* misc spelling
* adding mounted store tests to suite
* split out key
* relaxed key initialization
* always mount and lookup by path
* cleaned up and reorged tests
* test lookup by path
* add re-exports
* more re-exports
* fix warnings and re-exports
