Revert "Set source java version to 1.7. See #312" as this breaks compilation
Revert "Set source java version to 1.7. See #312" as this breaks compilation

This reverts commit 17bcebec6533218420c5df5925d7119b7e785395.

CliffYuan/netty,KeyNexus/netty,CliffYuan/netty,KeyNexus/netty