[reSIProcate] directory reorg -- ***IMPORTANT - MUST READ***

[Fischl jason]

In case this isn't obvious. If you are using resiprocate, dum or repro
it is important that you pay attention to this. The resulting changes
will require you to change your applications - although purely
cosmetically. The changes resolve some issues about how to use resip
and the resip utilities from other projects. It also eliminates the
very confusing os subdirectory that really had nothing to do with os
independence.

Migration Guidelines: 

I. #include changes: 
- change #include "resiprocate/os/blah.hxx" -> "rutil/blah.hxx"
- change #include "resiprocate/dum/blah.hxx" -> "resip/dum/blah.hxx"
- change #include "resiprocate/blah.hxx" -> "resip/stack/blah.hxx"
- change #include "resiprocate/dns/blah.hxx" -> "rutil/dns/blah.hxx"

II. Other changes
- If you relied on the sip/resiprocate/build directory it is now in build
- repro, build, contrib, tfm are now toplevel and parallel to resip
- there is a toplevel Makefile that builds everything

Anyways, please read this. 

Jason