Added require.sh to check if composer is installed

scripts/dev.sh

@@ -1,6 +1,10 @@
 #! /usr/bin/env bash
-# You can execute this file to install wallabag dev environmnet
-# eg: `sh install.sh prod`
+# You can execute this file to install wallabag dev environment
+# eg: `sh dev.sh`
+
+DIR="${BASH_SOURCE%/*}"
+if [[ ! -d "$DIR" ]]; then DIR="$PWD"; fi
+. "$DIR/require.sh"
 
 composer install
 php bin/console wallabag:install