Call cfn-create-aws-symlinks in boothook.sh
Call cfn-create-aws-symlinks in boothook.sh

Images which have heat-cfntools installed from rpm or deb
will not have cfn tool links in /opt/aws/bin.

This change runs cfn-create-aws-symlinks during cloud-init
boothook.sh. It should do the following:
* if no cfn tools exist in /opt/aws/bin, symlinks from /usr/bin
  will be created
* if cfn tools exist in /opt/aws/bin, no symlinks are created
* if cfn-create-aws-symlinks doesn't exist, there will be no effect

This is required to use a vanilla Fedora 20 cloud image with heat,
which has heat-cfntools pre-installed.

Change-Id: I5426fdad3031f91b4b9c1f9c9c19ac9cc42cf2dd

ntt-sic/heat,rh-s/heat,pratikmallya/heat,cryptickp/heat,cwolferh/heat-scratch,maestro-hybrid-cloud/heat,openstack/heat,jasondunsmore/heat,cwolferh/heat-scratch,openstack/heat,NeCTAR-RC/heat,maestro-hybrid-cloud/heat,dragorosson/heat,rdo-management/heat,gonzolino/heat,redhat-openstack/heat,srznew/heat,gonzolino/heat,redhat-openstack/heat,cryptickp/heat,ntt-sic/heat,srznew/heat,steveb/heat,pshchelo/heat,dims/heat,steveb/heat,noironetworks/heat,NeCTAR-RC/heat,dims/heat,takeshineshiro/heat,rh-s/heat,noironetworks/heat,pshchelo/heat,miguelgrinberg/heat,jasondunsmore/heat,takeshineshiro/heat,miguelgrinberg/heat,rdo-management/heat,pratikmallya/heat,dragorosson/heat