core: Add support for creating in memory tar

Change-Id: I090ab5f9323dca57e8de191c1bc32cd5a164b71d
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: HttpConnManager - add explicit connection timeout

This patch adds http connection timeout to the connections manager used
to initiate http connections - the connection timeout specifies a
timeout to be used until connection is established. Currently we pass
the timeout to the XmlRpcClientConfig only, therefore we can't count on
it that when we'll use the HTTP connection outside of the XML-RPC
transport layer timeout won't be encounterd.

Change-Id: I4e927ce28c8fdd9bcdcdb37e23b8d45c7515fd55
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: persist updated vm/template ovf config

When a vm/template ovf configuration is generated succesfully, persist
the updated configuration to the db.

Change-Id: Ic891429a2a7d055fbd1927e878ae7e0f8b7c9fd9
Signed-off-by: Liron Aravot <laravot@redhat.com>
core: create disk with passed description

When description is being passed it should be used when performing the
vdsm call.

Change-Id: I2216b3cfb6c880b9d1288e2e7aca1ec2a17c4b25
Signed-off-by: Liron Aravot <laravot@redhat.com>