Add PlayerBookEditEvent.  Adds BUKKIT-1995
Event related to book & quill and written book items.
Updated version to 1.5.2-R1.0 in pom.xml for RB.
Updated version to 1.5.2-R1.1-SNAPSHOT for development towards next release.
Define EntitySpawnEvent and SpawnerSpawnEvent. Adds BUKKIT-267 and BUKKIT-1559