Using greased for ByteArrayIO

Hi Peter, 

I pushed a version of nippy using the latest grease and ran tests on carmine using it. 
It compiles fine now, you can see for yourself using this branch: https://github.com/mpenet/carmine/tree/clojars 

* the build on travis for carmine using this nippy build: https://travis-ci.org/mpenet/carmine/builds/8209037

* the nippy build in question https://travis-ci.org/mpenet/nippy