Set curl as the default source install method

As much faster than git clone

Change-Id: I173592f1efceac61b49c37f994004cc41c641ae0
Closes-Bug: #1481670

docker/centos/source/cinder-app/cinder-base/.buildinfo

@@ -2,7 +2,6 @@
 
 COMPONENT=cinder
 SOURCE_INSTALL_AVAILABLE=1
-SOURCE_INSTALL_METHOD=curl
 
 # Used for git install method
 : ${CLONE_FROM:=https://github.com/openstack/cinder}

docker/centos/source/neutron/neutron-base/.buildinfo

 # Build info specific to this image. All values can be overridden in .buildconf
 
-SOURCE_INSTALL_METHOD=curl
 COMPONENT=neutron
 SOURCE_INSTALL_AVAILABLE=1
 

docker/centos/source/nova/nova-base/.buildinfo

 # Build info specific to this image. All values can be overridden in .buildconf
 
-SOURCE_INSTALL_METHOD=curl
 COMPONENT=nova
 SOURCE_INSTALL_AVAILABLE=1
 

tools/gen-source-tar.sh

@@ -2,7 +2,7 @@
 
 set -e
 
-: ${SOURCE_INSTALL_METHOD:=git}
+: ${SOURCE_INSTALL_METHOD:=curl}
 : ${GIT_REF:=master}
 : ${LOCAL_SOURCE:=/tmp/${COMPONENT}}