New Error

[SEVERE] Could not load 'plugins\testplugin.jar' in folder 'plugins':
java.lang.UnsupportedClassVersionError: com/github/klutch2013/TestPlugin/helloworld : Unsupported major.minor version 51.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClassCond(Unknown Source)
	at java.lang.ClassLoader.defineClass(Unknown Source)
	at java.security.SecureClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.access$000(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:41)
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:29)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131)
	at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:285)
	at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:200)
	at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:156)
	at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:132)
	at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigurationManager.java:52)
	at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:148)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408)
	at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)