16:23:35 [INFO] This server is running CraftBukkit version git-Spigot-jenkins-Li
berate_Spigot-30 (MC: 1.4.7) (Implementing API version Unknown-Version)
16:23:36 [SEVERE] java.lang.UnsupportedClassVersionError: com/rb2750/Pets/Main :
Unsupported major.minor version 51.0
16:23:36 [SEVERE]       at java.lang.ClassLoader.defineClass1(Native Method)
16:23:36 [SEVERE]       at java.lang.ClassLoader.defineClassCond(Unknown Source)

16:23:36 [SEVERE]       at java.lang.ClassLoader.defineClass(Unknown Source)
16:23:36 [SEVERE]       at java.security.SecureClassLoader.defineClass(Unknown Source)
16:23:36 [SEVERE]       at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:73)
16:23:36 [SEVERE]       at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:32)
16:23:36 [SEVERE]       at java.lang.ClassLoader.loadClass(Unknown Source)
16:23:36 [SEVERE]       at java.lang.ClassLoader.loadClass(Unknown Source)
16:23:36 [SEVERE]       at java.lang.Class.forName0(Native Method)
16:23:36 [SEVERE]       at java.lang.Class.forName(Unknown Source)
16:23:36 [SEVERE]       at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:144)
16:23:36 [SEVERE]       at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:307)
16:23:36 [SEVERE]       at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:231)
16:23:36 [SEVERE]       at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:265)
16:23:36 [SEVERE]       at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:243)
16:23:36 [SEVERE]       at net.minecraft.server.PlayerList.<init>(PlayerList.java:55)
16:23:36 [SEVERE]       at net.minecraft.server.DedicatedPlayerList.<init>(SourceFile:11)
16:23:36 [SEVERE]       at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:104)
16:23:36 [SEVERE]       at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:405)
16:23:36 [SEVERE]       at net.minecraft.server.ThreadServerApplication.run(SourceFile:849)
16:23:36 [SEVERE] Could not load 'plugins\Pets.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.ClassNotFoundException: com/rb2750/Pets/Main
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:155)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:307)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:231)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:265)
        at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:243)
        at net.minecraft.server.PlayerList.<init>(PlayerList.java:55)
        at net.minecraft.server.DedicatedPlayerList.<init>(SourceFile:11)
        at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:104)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:405)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.ClassNotFoundException: com/rb2750/Pets/Main
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:144)
        ... 9 more