Implement fetch (#4)

* Implement fetch & launch action
* Fix scroll behavior
* Remove horizontal scrollbar
* Add stubs for filling username / password
* Don't pre-filter for chrome:// URLs
* Add inject.js

src/inject.js

@@ -0,0 +1,18 @@
+(function() {
+    /**
+     * Fill password
+     *
+     * @since 3.0.0
+     *
+     * @param object login Login fields
+     * @return void
+     */
+    function fillLogin(login) {
+        alert("Fill login: " + JSON.stringify(login));
+    }
+
+    // set window object
+    window.browserpass = {
+        fillLogin: fillLogin
+    };
+})();