Put the password generator into a real .sh file (part 2)

Use my-passwords.yml in sandbox.sh

(cherry picked from commit f3970b73af316502722e6153f11af52f7b61112d)
(cherry picked from commit 81cc046ff09e69642eeb7cb82aa1f7b08b28c649)

util/install/generate-passwords.sh

@@ -4,9 +4,9 @@
 # a new file just like it, with the generated values.
 
 TARGET=${OPENEDX_RELEASE-master}
-wget -q https://raw.githubusercontent.com/edx/configuration/$TARGET/playbooks/sample_vars/passwords.yml -O passwords-template.yml
+wget -q "https://raw.githubusercontent.com/edx/configuration/$TARGET/playbooks/sample_vars/passwords.yml" -O passwords-template.yml
 
-while IFS= read line; do 
+while IFS= read -r line; do
     # Make a random string. SECRET_KEY's should be longer.
     length=35
     if [[ $line == *SECRET_KEY* ]]; then

util/install/sandbox.sh

@@ -66,6 +66,11 @@ for var in ${VERSION_VARS[@]}; do
   fi
 done
 
+# my-passwords.yml is the file made by generate-passwords.sh.
+if [[ -f my-passwords.yml ]]; then
+    EXTRA_VARS="-e@my-passwords.yml $EXTRA_VARS"
+fi
+
 CONFIGURATION_VERSION=${CONFIGURATION_VERSION-${OPENEDX_RELEASE-master}}
 
 ##