[21:21:03] [Server thread/ERROR]: Could not load 'plugins/RPGMissions_-_0.6.1.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/Cracksn0w/RPG_Missions/Main : Unsupported major.minor version 52.0
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:133) ~[minecraft_server.jar:git-Spigot-1649]
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:341) ~[minecraft_server.jar:git-Spigot-1649]
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:263) [minecraft_server.jar:git-Spigot-1649]
    at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugins(CraftServer.java:369) [minecraft_server.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.DedicatedServer.init(DedicatedServer.java:152) [minecraft_server.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:458) [minecraft_server.jar:git-Spigot-1649]
    at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [minecraft_server.jar:git-Spigot-1649]
Caused by: java.lang.UnsupportedClassVersionError: com/Cracksn0w/RPG_Missions/Main : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.7.0_51]
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800) ~[?:1.7.0_51]
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.7.0_51]
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) ~[?:1.7.0_51]
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71) ~[?:1.7.0_51]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361) ~[?:1.7.0_51]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355) ~[?:1.7.0_51]
    at java.security.AccessController.doPrivileged(Native Method) ~[?:1.7.0_51]
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354) ~[?:1.7.0_51]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[minecraft_server.jar:git-Spigot-1649]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[minecraft_server.jar:git-Spigot-1649]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425) ~[?:1.7.0_51]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ~[?:1.7.0_51]
    at java.lang.Class.forName0(Native Method) ~[?:1.7.0_51]
    at java.lang.Class.forName(Class.java:270) ~[?:1.7.0_51]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[minecraft_server.jar:git-Spigot-1649]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[minecraft_server.jar:git-Spigot-1649]
    ... 6 more