Dataspace juju

[Christian Prochaska]

In Daniel's test case, attaching a single dataspace of size 107374182 to
an Rm_session of the same size fails, because in 'Rm_session::attach()'
the size to be attached gets rounded up to page granularity and the size
of the Rm_session does not have page granularity. I wonder if an
exception should be thrown if one tries to create an Rm_session with an
'vm_size' which does not have page granularity?