I am building a Single node Psuedo Cluster using the latest CDH 5.4 and Cloudera Documentation.  The zookeeper server fails to startup with the following message in *.out file:

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/zookeeper/server/quorum/QuorumPeerMain : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
Could not find the main class: org.apache.zookeeper.server.quorum.QuorumPeerMain. Program will exit.

Also here is my /etc/zookeeper/conf/zoo.cfg file contents:

maxClientCnxns=50
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
dataDir=/var/lib/zookeeper
# the port at which the clients will connect
clientPort=2181
# the directory where the transaction logs are stored.
dataLogDir=/var/lib/zookeeper
# Export JAVA_HOME and JRE_HOME
export JAVA_HOME=/opt/jdk1.7.0_75
export JRE_HOME=/opt/jdk1.7.0_75/jre
export CLASSPATH=$CLASSPATH:/usr/lib/zookeeper/zookeeper.jar

All services including hive, hbase and spark are working with 5.3. and older.