Revert "Netty"

This reverts commit f0b55b71fffee10d904c3933430272aed5da4230.

Conflicts:
	pom.xml
	src/main/java/org/spigotmc/MultiplexingServerConnection.java
	src/main/java/org/spigotmc/netty/NettyNetworkManager.java
	src/main/java/org/spigotmc/netty/OutboundManager.java
	src/main/resources/configurations/bukkit.yml
Update maven-compiler-plugin, because Jenkins

otherwhise gets drunk together with maven on a lonely island, ok?

Signed-off-by: XemsDoom <moser.luca@gmail.com>
Resolve maven compilation failure
Signed-off-by: Steven Downer <grinch@outlook.com>