Description of problem:
libvirt-client is not able to set dhcp lease time - that means it's set for default 8 hours. There should be some mechanism how to pass this option to dnsmasq or copy "default" values from dnsmasq config to temporary config file which virtual-manager creates and uses for dnsmasq execution.

There is current "network" scheme - DHCP part:
- SNIP -
              <!-- Define the range(s) of IP addresses that the DHCP
                   server should hand out -->
              <element name="dhcp">
                <zeroOrMore>
                  <element name="range">
                    <attribute name="start"><ref name="ipv4Addr"/></attribute>
                    <attribute name="end"><ref name="ipv4Addr"/></attribute>
                  </element>
                </zeroOrMore>
                <zeroOrMore>
                  <element name="host">
                    <attribute name="mac"><ref name="uniMacAddr"/></attribute>
                    <attribute name="name"><text/></attribute>
                    <attribute name="ip"><ref name="ipv4Addr"/></attribute>
                  </element>
                </zeroOrMore>
                <optional>
                  <element name="bootp">
                    <attribute name="file"><ref name="filePath"/></attribute>
                    <optional>
                      <attribute name="server"><ref name="dnsName"/></attribute>
                    </optional>
                  </element>
                </optional>
              </element>
- SNIP -

Version-Release number of selected component (if applicable):
libvirt-client-0.10.2-29.el6

How reproducible:
Always

Steps to Reproduce:
1. run virtual machine - there is no option for dhcp lease time
2. ps aux | grep dnsmasq
3. see that running dnsmasq and temporary config file don't contain information about dhcp lease time: "--conf-file=" and "--dhcp-range" options

Actual results:
No way how to set dhcp lease time when virtual machine runs via virtual manager

Expected results:
New option in virtual manager / virtual manager is able to copy default values from dnsmasq config file into virtual manager's temporary config file

Additional info: