removed duplicate inISR prototype
test: fix bloom filter test
simplified sched_switch

sched_switch can check ISR itself.
Merge pull request #713 from OlegHahm/sched_switch_simplification

core: move inISR check into sched_switch
Adds test for riot threads.

The test uses riot threads to calculate the factorial of 12,
with one thread for each multiplication. The core mutex is
used for synchronization.
Merge pull request #780 from mehlis/fix-bloom-test

test: fix bloom filter test
Merge pull request #757 from josephnoir/add_test_thread_factorial

tests: Add test for riot thread
remove hwtimer from test_irq
Merge pull request #788 from LudwigOrtmann/714_fixup

remove hwtimer from test_irq
Changes to `thread_wakeup`

`thread_wakeup` did not check if target pid is invalid.

`thread_wakeup` used `dINT` and `eINT` directly.
It should use `disableIRQ` and `restoreIRQ` instead, because there might
be other (good) reasons why one might want to call `thread_wakeup` with
interrupts disabled.

`thread_wakeup` yielded even if the other thread had a lower priority
than the current thread.
Rebase after #713