Fix several nagging bugs in lxc-destroy
Fix several nagging bugs in lxc-destroy

Don't delete a running container.  If it's running, abort the delete
unless a new '-f' (force) flag is given, in which case, stop it first.

Handle the case where we can't find $rootfs in config

Fix broken detection of lvm backing store

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@canonical.com>
Signed-off-by: Daniel Lezcano <3211518dd4d87cb3f7ee12cb52e14b7fb2bc0446@fr.ibm.com>

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