Prompt user, then run mozroots if they consent

Instead of making the user run mozroots themselves, we should probably
run it for them if (and ONLY if) they consent.

Also make sure they really need it, by checking both the user and system
certificate stores before prompting them.

build.sh

@@ -25,10 +25,24 @@ function run() {
   fi
 }
 
+function yesno() {
+  # NOTE: Defaults to NO
+  read -p "$1 [y/N] " ynresult
+  case "$ynresult" in
+    [yY]*) true ;;
+    *) false ;;
+  esac
+}
+
+set +e
 run $PAKET_BOOTSTRAPPER_EXE
+bootstrapper_exitcode=$?
+set -e
 
 if [[ "$OS" != "Windows_NT" ]] &&
-       [ $(certmgr -list -c Trust | grep X.509 | wc -l) -le 1 ]
+       [ $bootstrapper_exitcode -ne 0 ] &&
+       [ $(certmgr -list -c Trust | grep X.509 | wc -l) -le 1 ] &&
+       [ $(certmgr -list -c -m Trust | grep X.509 | wc -l) -le 1 ]
 then
   echo "Your Mono installation has no trusted SSL root certificates set up."
   echo "This may result in the Paket bootstrapper failing to download Paket"
@@ -39,8 +53,17 @@ then
   echo "    mozroots --import --sync"
   echo ""
   echo "This will import over 100 SSL root certificates into your Mono"
-  echo "certificate repository. Then try running this script again."
-  exit 1
+  echo "certificate repository."
+  echo ""
+  if yesno "Run 'mozroots --import --sync' now?"
+  then
+    mozroots --import --sync
+  else
+    echo "Attempting to continue without running mozroots. This might fail."
+  fi
+  # Re-run bootstrapper whether or not the user ran mozroots, because maybe
+  # they fixed the problem in a separate terminal window.
+  run $PAKET_BOOTSTRAPPER_EXE
 fi
 
 run $PAKET_EXE restore