added spark core board

- [x] based on https://github.com/RIOT-OS/RIOT/pull/1752 <- wait for its merge first!

TODO:
- [x] test
- [x] restore examples/hello-world
- [x] extend blacklists
- [x] add flash/debug scripts and make targets
- [x] update wiki
- [x] fix doxygen/authorship
`file does not have a C++ compatible header: 'boards/spark-core/include/board.h'`