Added checkpoints

	new file:   tools/src/main/java/com/google/auroracoin/tools/BuildCheckpoints.java
Some fixes

	modified:   core/src/main/java/com/google/bitcoin/core/NetworkParameters.java
	modified:   core/src/main/java/org/auroracoin/AuroraCoinParams.java
	modified:   tools/src/main/java/com/google/auroracoin/tools/BuildCheckpoints.java