Implemented PDF Viewer in the browser itself

- Implemented PDF viewer in the browser itself.
- Now Uploaded PDF files can directly viewed in the body.
- The PDF viewer is with set of handy tools.
- Also provided separate link to open PDF in the full screen in new tab.

**NOTE:** Please do ```bower install```

**TEST:**
- Upload new PDF file and open the detail view of it.
- Or open detail view of already uploaded PDF file.