* [mac filter] add rssfilter support and integrate whitelist/blacklist
- provide RssIn filter function to fix the received signal strength for test purpose.
- provide Address filter function which integrates whitelist and blacklist, save (~300B) RAM.
- update cli and spinel-cli to reflect new otLinkFilterX() APIs.
- keep whitelist/blacklist spinel properties the same as before while implemented with new otLinkFilterX() APIs.
- THCI: add setOutBoundLinkQuality() API for DEV-1530
- THCI: update Allow/Block relative APIs
- update some test scripts due to new OT_ERROR_ALEADY when adding duplicate address to whitelist
* update for comments
* add MAC_FIXED_RSS spinel property
* rebase and apply new OutboundFrameBegin(aHeader)
* update OpenThread.py
* Add a new build target: ncp-mtd.
* Platform with "--enable-ftd" build option will build both MTD and FTD.
* Platform without "--enable-ftd" build option will only build MTD.