Bukkit

I'm getting a problem. I put the Torture.jar in the plugins folder, but when I run the LaunchServer.command, at one point I get this error:

"05:18:47 [SEVERE] Could not load 'plugins/Torture.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/Riderj/Torture/Torture : Unsupported major.minor version 51.0
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:151)
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
    at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:213)
    at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:189)
    at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigurationManager.java:53)
    at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:166)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:432)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.UnsupportedClassVersionError: com/Riderj/Torture/Torture : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    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(ClassLoader.java:306)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:247)
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:140)
    ... 8 more"

My other plugins are:
*MobDisguise
*VanishNoPacket
*Scarest (Outdated and doesn't work)
*NoSwear
*Lockette
*Thor
*WelcomeRulezz

What is your JDK version?

@IronCrystal: Go

All my server files are up to date.

@Diamondmatter: Go

That's not what I asked. What is your JDK version? I don't want your Bukkit version.