Merge pull request #13 from modax/bug/quote-for-z-test

Quote values for -z test.

Author: bruno-

scripts/shared.sh

@@ -2,7 +2,7 @@ get_tmux_option() {
 	local option=$1
 	local default_value=$2
 	local option_value=$(tmux show-option -gqv "$option")
-	if [ -z $option_value ]; then
+	if [ -z "$option_value" ]; then
 		echo $default_value
 	else
 		echo $option_value