deploy: make extra sure we're iterating over single files

should be default behaviour for ls when not run in a terminal, but
better be sure...
Signed-off-by: Mattia Rizzolo <mattia@debian.org>

deploy

@@ -39,7 +39,7 @@ if [[ ! -d "${env}" ]]; then
     echo
 
     echo "available environments:"
-    for available in `ls "${DIR_ENVIRONMENTS}"`; do
+    for available in `ls -1 "${DIR_ENVIRONMENTS}"`; do
         echo " - ${available}"
     done
     exit 1
@@ -49,7 +49,7 @@ if [[ ! -f "${playbook_file}" ]]; then
     echo
 
     echo "available playbooks:"
-    for available in `ls "${DIR_PLAYBOOKS}"`; do
+    for available in `ls -1 "${DIR_PLAYBOOKS}"`; do
         echo " - `echo "${available}" | sed 's/\.yml$//'`"
     done
     exit 1