Randomize tunnel id query to avoid contention
Randomize tunnel id query to avoid contention

When networks are created rapidly, neutron-servers compete
for segmentation ids which creates too much contention and
may lead to inability to choose available id in hardcoded amount
of attempts (11)
Randomize tunnel id selection so that condition is not hit.

Change-Id: I7068f90fe4927e6e693f8a62cb704213b2da2920
Related-Bug: #1382064
Closes-Bug: #1454434

paninetworks/neutron,wenhuizhang/neutron,mandeepdhami/neutron,mmnelemane/neutron,sebrandon1/neutron,eonpatapon/neutron,sebrandon1/neutron,cloudbase/neutron,cisco-openstack/neutron,javaos74/neutron,suneeth51/neutron,SmartInfrastructures/neutron,apporc/neutron,mahak/neutron,mahak/neutron,mattt416/neutron,dims/neutron,suneeth51/neutron,swdream/neutron,noironetworks/neutron,asgard-lab/neutron,silenci/neutron,igor-toga/local-snat,yanheven/neutron,jacknjzhou/neutron,dhanunjaya/neutron,bgxavier/neutron,jacknjzhou/neutron,takeshineshiro/neutron,silenci/neutron,openstack/neutron,chitr/neutron,neoareslinux/neutron,wenhuizhang/neutron,eayunstack/neutron,jerryz1982/neutron,wolverineav/neutron,dhanunjaya/neutron,antonioUnina/neutron,jumpojoy/neutron,igor-toga/local-snat,swdream/neutron,cisco-openstack/neutron,sasukeh/neutron,JianyuWang/neutron,glove747/liberty-neutron,huntxu/neutron,cloudbase/neutron,eayunstack/neutron,shahbazn/neutron,adelina-t/neutron,skyddv/neutron,shahbazn/neutron,SmartInfrastructures/neutron,barnsnake351/neutron,jerryz1982/neutron,mmnelemane/neutron,SamYaple/neutron,antonioUnina/neutron,yanheven/neutron,mattt416/neutron,neoareslinux/neutron,openstack/neutron,dims/neutron,glove747/liberty-neutron,sasukeh/neutron,mahak/neutron,NeCTAR-RC/neutron,huntxu/neutron,NeCTAR-RC/neutron,watonyweng/neutron,chitr/neutron,apporc/neutron,noironetworks/neutron,klmitch/neutron,mandeepdhami/neutron,JianyuWang/neutron,vivekanand1101/neutron,JioCloud/neutron,klmitch/neutron,SamYaple/neutron,JioCloud/neutron,barnsnake351/neutron,takeshineshiro/neutron,skyddv/neutron,javaos74/neutron,wolverineav/neutron,openstack/neutron,bgxavier/neutron,adelina-t/neutron,eonpatapon/neutron,MaximNevrov/neutron,MaximNevrov/neutron,watonyweng/neutron,paninetworks/neutron,asgard-lab/neutron,jumpojoy/neutron,bigswitch/neutron,bigswitch/neutron,vivekanand1101/neutron