SCHEMA-793. Implement AsyncKijiResult.

Implemented AsyncKijiResult, AsyncPagedKijiResult, AsyncMaterializedKijiResult,
AsyncKijiResultScanner, AsyncDataRequestAdapter, and associated tests.

issue: https://jira.kiji.org/browse/SCHEMA-793
param comments should be full sentences without the parameter name, so something like:

        @param kijiFilter The KijiColumnFilter to convert.