split utils package

[jmesnil]

org.hornetq.utils package contains utilities classes which are used by the client or the server, or both.

I'll split it into 2 packages to make it clear what's part of the client API and what's not.

From the top of my mind, we'd have

org.hornetq.utils

  - Pair

  - SimpleString

org.hornetq.server.utils

  - all other classes used by the server only

[timfox]

IMHO I would just move SimpleString and Pair out of the utils package and into a higher level package

[jmesnil]

fine, i'll move them to org.hornetq (can't go higher than that package )