org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: me/mrtoucan/potpvp/PotPvP : Unsupported major.minor version 52.0
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:133) ~[spigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:341) ~[spigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:263) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugins(CraftServer.java:369) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.reload(CraftServer.java:864) [spigot.jar:git-Spigot-1649]
        at org.bukkit.Bukkit.reload(Bukkit.java:301) [spigot.jar:git-Spigot-1649]
        at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:23) [spigot.jar:git-Spigot-1649]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:181) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.dispatchCommand(CraftServer.java:767) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.dispatchServerCommand(CraftServer.java:753) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.DedicatedServer.aB(DedicatedServer.java:326) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:290) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [spigot.jar:git-Spigot-1649]
Caused by: java.lang.UnsupportedClassVersionError: me/mrtoucan/potpvp/PotPvP : Unsupported major.minor version 52.0
        at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.7.0_121]
        at java.lang.ClassLoader.defineClass(ClassLoader.java:803) ~[?:1.7.0_121]
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.7.0_121]
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:442) ~[?:1.7.0_121]
        at java.net.URLClassLoader.access$100(URLClassLoader.java:64) ~[?:1.7.0_121]
        at java.net.URLClassLoader$1.run(URLClassLoader.java:354) ~[?:1.7.0_121]
        at java.net.URLClassLoader$1.run(URLClassLoader.java:348) ~[?:1.7.0_121]
        at java.security.AccessController.doPrivileged(Native Method) ~[?:1.7.0_121]
        at java.net.URLClassLoader.findClass(URLClassLoader.java:347) ~[?:1.7.0_121]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot.jar:git-Spigot-1649]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425) ~[?:1.7.0_121]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ~[?:1.7.0_121]
        at java.lang.Class.forName0(Native Method) ~[?:1.7.0_121]
        at java.lang.Class.forName(Class.java:278) ~[?:1.7.0_121]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot.jar:git-Spigot-1649]
        ... 14 more