Project korra error

[19:48:26 ERROR]: Could not load 'plugins/ProjectKorra.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/projectkorra/projectkorra/ProjectKorra : Unsupported major.minor version 51.0
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:292) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:739) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.Bukkit.reload(Bukkit.java:535) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchServerCommand(CraftServer.java:627) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at net.minecraft.server.v1_8_R3.DedicatedServer.aO(DedicatedServer.java:412) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:375) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-db6de12-18fbb24]
	at java.lang.Thread.run(Thread.java:695) [?:1.6.0_65]
Caused by: java.lang.UnsupportedClassVersionError: com/projectkorra/projectkorra/ProjectKorra : Unsupported major.minor version 51.0
	at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.6.0_65]
	at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637) ~[?:1.6.0_65]
	at java.lang.ClassLoader.defineClass(ClassLoader.java:621) ~[?:1.6.0_65]
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) ~[?:1.6.0_65]
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) ~[?:1.6.0_65]
	at java.net.URLClassLoader.access$000(URLClassLoader.java:58) ~[?:1.6.0_65]
	at java.net.URLClassLoader$1.run(URLClassLoader.java:197) ~[?:1.6.0_65]
	at java.security.AccessController.doPrivileged(Native Method) ~[?:1.6.0_65]
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190) ~[?:1.6.0_65]
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306) ~[?:1.6.0_65]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247) ~[?:1.6.0_65]
	at java.lang.Class.forName0(Native Method) ~[?:1.6.0_65]
	at java.lang.Class.forName(Class.java:249) ~[?:1.6.0_65]
	at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
	... 14 more