change default target to native for most projects

implements https://github.com/RIOT-OS/RIOT/issues/202
some projects don't make sense for native because they test hardware
    native does not support
put spaces around all = characters
fix some indentations for if/endifs
set all RIOTBASE paths to ../../RIOT
fix extraneous text after else directive in tlayer/Makefile
fix pingpong printf
fix pingpong_sync printf
fix pingpong_sync project name
make max_cache_entries a parameter
Merge pull request #63 from mehlis/ccn-lite-follow-up

make max_cache_entries a parameter
Merge pull request #62 from LudwigOrtmann/projects_update

project default target update + clean up