Removal of unexisting dependency

This artifact does not exist (it should rather be org.jboss.aerogear:aerogear-netty-codec-sockjs, from https://github.com/aerogear/aerogear-simplepush-server/commit/a45245728b57e39ae5f63e01aadc4cf0c3c6b6b4#diff-0bc5f6b3f39d5e616b16132668b36b8bL61).
It should be removed anyway, as we would not declare AeroGear dependencies into AeroGear BOMs