add -t param to provision clone + param check

utils/provision

@@ -32,6 +32,7 @@ read -r -d '' usage <<-'EOF'
   -i         Configure OpenDKIM.
   -c         Configures DNS on Namecheap.
   -d         Enables debug mode
+  -t         Checkout a specific tag or branch
   -h         This page
 EOF
 
@@ -103,7 +104,7 @@ function buy_domain_name () {
 }
 
 function application () {
-  git clone https://${arg_a}.git /data/domains/${arg_u}
+  git clone https://${arg_a}.git /data/domains/${arg_u} -t ${arg_t}
   cd /data/domains/${arg_u}
   if [ -f ./scripts/install ]; then
     export URL=${arg_u}
@@ -201,6 +202,8 @@ fi
 
 [ -z "${arg_u}" ]     && help      "URL is required."
 [ -z "${LOG_LEVEL}" ] && emergency "Cannot continue without LOG_LEVEL."
+# tags/branch for modules 
+[ -z "${arg_t}" ]     && arg_t=master
 
 
 ### Runtime