Hmm.... Looked at the full log you posted, which wasn't very full may I add, and what you posted in the spoiler was not relevant at all...
In the log, you have
Code:
[LIST=1]
[*]Caused by: java.lang.ClassNotFoundException: net.minecraftforge.fml.relauncher.IFMLLoadingPlugin
[*] at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.11.jar:?]
[*] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
[*] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
[*] ... 23 more
[*]Caused by: java.lang.NullPointerException
[*] at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182) ~[launchwrapper-1.11.jar:?]
[*] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
[*] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
[*] ... 23 more
[/LIST]
Which suggests that you are missing a mod. But I have no idea what, as I said, that log is ugly, and doesn't give much in terms of detail