Set location to src on session restore load. Fixes #131

I feel like there's probably a better way to do this so we can preserve
the original src, but I don't think there is exposed by electron today.
This should be fine for now though.

Added a note into the tests issue for this for session store.

Auditors: @bridiver

app/sessionStore.js

@@ -68,6 +68,10 @@ module.exports.cleanSessionData = (sessionData) => {
     frame.canGoBack = false
     frame.canGoForward = false
 
+    // Set the frame src to the last visited location
+    // or else users will see the first visited URL.
+    frame.src = frame.location
+
     // If a blob is present for the thumbnail, create the object URL
     if (frame.thumbnailBlob) {
       try {