Small refactoring: Now xenstore_start_page and console_start_page is in the Start_page module instead of Console/Xs.
Mirage now just simply instanciate a standard XenStore client, and do not redefine its methods anymore.
Hide Xs.IO module: This should be used for exactly one instanciation as mirage does not multiplex the access to the xenstore.
Fixed atomic_stubs.
Merge pull request #103 from vbmithr/no-xenstore

No xenstore
Removing misleading function Netif.get_writebuf.