React: Fixed version detection (#2117)

* React: Fixed version detection

Example sites which are using React:
- Slack
- Dropbox
- Imgur
On all it works fine with PascalCase "React".

* React: Readded old version detection

* React: Removed unnecessary js check

src/apps.json

@@ -7888,8 +7888,8 @@
         12
       ],
       "js": {
-        "React": "",
+        "react.version": "(.*)\\;version:\\1",
-        "react.version": "(.*)\\;version:\\1"
+        "React.version": "(.*)\\;version:\\1"
       },
       "html": "<[^>]+data-react",
       "icon": "React.png",