Description of problem:
It is allowed to create a instance type with graphic protocol: spice and video type cirrus. 
Changing the video type and checking the instance type console again shows no change.

Version-Release number of selected component (if applicable):
ovirt-engine-4.3.0-0.5.alpha1.el7.noarch

How reproducible:
100%

Steps to Reproduce:
1. Create a new instance type for example in rest api:
POST https://<engine-fqdn>/ovirt-engine/api/instancetypes?create
<instance_type>
    <name>test_instance_type</name>
    <description>I am a test</description>
    <console>
        <enabled>true</enabled>
    </console>
    <cpu>
        <topology>
            <cores>2</cores>
            <sockets>2</sockets>
            <threads>2</threads>
        </topology>
    </cpu>
    <display>
        <disconnect_action>NONE</disconnect_action>
        <monitors>4</monitors>
        <single_qxl_pci>true</single_qxl_pci>
        <smartcard_enabled>true</smartcard_enabled>
        <type>spice</type>
    </display>
    <high_availability>
        <enabled>true</enabled>
        <priority>2</priority>
    </high_availability>
    <io>
        <threads>2</threads>
    </io>
    <memory>268435456</memory>
    <memory_policy>
        <guaranteed>268435456</guaranteed>
        <max>1073741824</max>
    </memory_policy>
    <migration>
        <auto_converge>true</auto_converge>
        <compressed>false</compressed>
        <policy id="00000000-0000-0000-0000-000000000000"/>
    </migration>
    <migration_downtime>100</migration_downtime>
    <os>
        <boot>
            <devices>
                <device>network</device>
                <device>hd</device>
            </devices>
        </boot>
    </os>
    <soundcard_enabled>true</soundcard_enabled>
    <virtio_scsi>
        <enabled>true</enabled>
    </virtio_scsi>
</instance_type>
2. Check the console of the created instance type.
3. Edit the video type to QXL.
4. Check the instance type console again.

Actual results:
The instance type is created with spice, cirrus. Which is not supported.
Editing the video type doesn't actually change the instance type.

Expected results:
Instance type created with spice will be set with QXL. Editing the instance type will save the change of the video type.
Further more, if instance type is created with more than 1 monitor, allow only spice+qxl.

Additional info:
If a VM is created from a template with the instance type from step 1 using REST API. The VM creation will fail:
ERROR [org.ovirt.engine.api.restapi.resource.AbstractBackendResource] (default task-26) [] Operation Failed: [User is not authorized to perform this action., User is not authorized to perform this action., Cannot add VM. Illegal number of monitors is provided, max allowed number of monitors is 1 for VNC and the max number in the ValidNumOfMonitors configuration variable for SPICE.]