[fix] various fixes

scripts/install

 set -e
 
+RENEW_CERT_PATH=/opt/neutrinet/renew_cert
+
 install_renew_cert() {
     set -e
 
+    install_dir=$(pwd)
+
     sudo apt-get install -y python-virtualenv
 
-    sudo git clone https://github.com/neutrinet/renew_cert /opt
+    sudo git clone https://github.com/neutrinet/renew_cert $RENEW_CERT_PATH
 
     git checkout a6d09c2d77ce9bd4161d56e93fc5ce03187ad51c || echo ""
 
-    install_dir=$(pwd)
-
     cd /opt/renew_cert
 
     # I need system site packages otherwise moulinette is broken
@@ -21,11 +23,15 @@ install_renew_cert() {
 }
 
 renew_cert() {
-    cd /opt/renew_cert
+    set -e
+
+    install_dir=$(pwd)
+
+    cd $RENEW_CERT_PATH
     sudo ve/bin/python renew_from_cube.py
-}
 
-path=${path%/}
+    cd $install_dir
+}
 
 sudo yunohost app setting neutrinet version -v "0.1"