applications: set stack size correctly

The correct stack size for all examples and test applications correctly.
KERNEL_CONF_STACKSIZE_MAIN is the correct stack size for any thread
using printf.

Also adapted black lists accordingly.
sys/ps: s/float/int for runtime

The high precision isn't needed, use per mille instead.
Circumvents printf problems on some platforms.

Also: prevent division by zero.
sys/ps: fix comment style, superfluous declaration
Merge pull request #1370 from OlegHahm/fix_stack_sizes

applications: set stack size correctly
Merge pull request #1352 from LudwigOrtmann/nofloat

sys/ps: don't use float for runtime calculations