added obligation service
fixed some bugs
fixed some bugs
Merge branch 'for-distribution' into with-futures

Conflicts:
	src/main/scala/stapl/core/pdp/EvaluationCtx.scala
	src/main/scala/stapl/core/pdp/PDP.scala
Revert "Merge branch 'for-distribution' into with-futures"

This reverts commit 1a323e715631b584d77a347ebae542859280ce5b, reversing
changes made to d27d1bbdc5287cb8230eecf26eb369a19cd27246.