mno-async_writes/interface: Extended C++ generator to generate files with...

mno-async_writes/interface: Extended C++ generator to generate files with service constants and request message types per proc id for upcoming C++ TestRPCServer.
- generated/xtreemfs/get_request_message.h allows to obtain a new request message object for a given interface and proc id.
- {DIR,MRC,OSD}ServiceConstants.h files include constant variables for the proc ids of each service.

git-svn-id: https://xtreemfs.googlecode.com/svn/branches/mno-async_writes@2966 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534