Upgrade to Netty 4.2.4.Final

[mp911de]

Also, remove allocator property to verify that Netty has fixed the adaptive allocator bug, see #2087

[schauder]

Changed this issue to upgrade to 4.2.4 instead of 4.2.3 since the 4.2.3 version did not fix the index out of bounds problem when the allocator property was removed.