First functional web interface version.

- Simplify by now all html and javascript.
- Added a simple interface using go templates and plain javascript.
- Improved REST interface for the use case.
- Changed some properties into the config file to make it suitable for
future use cases.

Signed-off-by: Antonio Navarro Perez <antnavper@gmail.com>

torrent/templates/common_header.html

@@ -0,0 +1,8 @@
+<!-- Required meta tags -->
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
+
+<!-- Bootstrap CSS -->
+<link rel="stylesheet" href="assets/css/bootstrap.min.css">
+
+<title>{{.Title}}</title>