lxc-ubuntu: Default to current ubuntu release.
lxc-ubuntu: Default to current ubuntu release.

If can't match any valid release, use lucid.

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>
Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>
Signed-off-by: Daniel Lezcano <3211518dd4d87cb3f7ee12cb52e14b7fb2bc0446@fr.ibm.com>

LynxChaus/lxc,codebauss/lxc,szaszg/lxc,smoser/lxc,terceiro/lxc,regit/lxc,QingweiPeterLan/cs188-lxc,szaszg/lxc,Ponce/lxc,bmoar/lxc,QingweiPeterLan/cs188-lxc,efiop/lxc,szaszg/lxc,hkjolhede/lxc,lazy404/lxc,terceiro/lxc,GreatFruitOmsk/lxc,tych0/lxc,caglar10ur/lxc,abstrakraft/lxc-android-lxc,christiaan/lxc,hfuCN/lxc,sapun/lxc,ecarrara/lxc,DarknessBeforeDawn/lxc,thmo/lxc,smoser/lxc,JohnPeacockMessageSystems/lxc,ksperis/lxc,ysbnim/lxc,ostap/lxc,akshaykarle/lxc,jirislaby/lxc,jirislaby/lxc,ioops/lxc,GreatFruitOmsk/lxc,regit/lxc,lisongmin/lxc,hkjolhede/lxc,bostjan/lxc,rldleblanc/lxc,ioops/lxc,armcc/lxc,hallyn/lxc,thmo/lxc,hallyn/lxc,cjwatson/lxc,ss1h2a3tw/lxc,hkjolhede/lxc,major/lxc,glensc/lxc,cjwatson/lxc,lazy404/lxc,Pelagicore/lxc,smoser/lxc,ecarrara/lxc,akshaykarle/lxc,smoser/lxc,caglar10ur/lxc,LynxChaus/lxc,ksperis/lxc,aeris/lxc,ioops/lxc,ojkastl/lxc_Patches,regit/lxc,tych0/lxc,hallyn/lxc,bostjan/lxc,ojkastl/lxc_Patches,ostap/lxc,jirislaby/lxc,ysbnim/lxc,glensc/lxc,efiop/lxc,inokappa/lxc,Pelagicore/lxc,major/lxc,federicobriata/lxc,lazy404/lxc,ss1h2a3tw/lxc,major/lxc,aeris/lxc,ksperis/lxc,aeris/lxc,glensc/lxc,hfuCN/lxc,federicobriata/lxc,ojkastl/lxc_Patches,JohnPeacockMessageSystems/lxc,yubo/lxc,terceiro/lxc,rowhit/lxc,bostjan/lxc,lisongmin/lxc,fwilson42/lxc,abstrakraft/lxc-android-lxc,inokappa/lxc,Distrotech/lxc,Distrotech/lxc,codebauss/lxc,Ponce/lxc,potatosalad/lxc,christiaan/lxc,bmoar/lxc,thmo/lxc,fwilson42/lxc,rowhit/lxc,Ponce/lxc,raspberrypython/lxc,DarknessBeforeDawn/lxc,codebauss/lxc,fwilson42/lxc,hfuCN/lxc,GreatFruitOmsk/lxc,QingweiPeterLan/cs188-lxc,rldleblanc/lxc,ss1h2a3tw/lxc,armcc/lxc,akshaykarle/lxc,virajs/lxc,armcc/lxc,abstrakraft/lxc-android-lxc,LynxChaus/lxc,caglar10ur/lxc,Pelagicore/lxc,ecarrara/lxc,DarknessBeforeDawn/lxc,abstrakraft/lxc-android-lxc,bmoar/lxc,potatosalad/lxc,yubo/lxc,JohnPeacockMessageSystems/lxc,ojkastl/lxc_Patches,Distrotech/lxc,sapun/lxc,federicobriata/lxc,efiop/lxc,coconutpilot/lxc-gentoo-new,virajs/lxc,raspberrypython/lxc,ysbnim/lxc,tych0/lxc,weizhenwei/lxc,weizhenwei/lxc,virajs/lxc,rowhit/lxc,coconutpilot/lxc-gentoo-new,yubo/lxc,christiaan/lxc,sapun/lxc,cjwatson/lxc,rldleblanc/lxc,lisongmin/lxc,raspberrypython/lxc,weizhenwei/lxc