Replace qpid_host with qpid_hostname

This patch replaces `qpid_host` with `qpid_hostname` in both the
qpid manifest and the spec file class. `qpid_host` has been shipped
as the parameter to specify qpid's hostname, although the correct one is
`qpid_hostname`.

Closes-bug 1242715

Change-Id: I92b8da5a204180316f8117634a45154023551abd