* deletes the following files because they are deprecated since brooklyn 0.4
* delete core/src/main/java/brooklyn/entity/basic/PostStart.java
* delete core/src/main/java/brooklyn/entity/basic/PreStart.java
* delete core/src/main/java/brooklyn/entity/basic/PreStop.java
Merge pull request #737 from pveentjer/deletePrePostMethods

* deletes the following files because they are deprecated since brooklyn...