Update schedule not more than once per minute

Refs #1
Update popup every 10 seconds instead of 0.1

Refs #1
Refresh popup when destination is changed

Refs #1
Do not use localStorage for schedule storing

Refs #1
Regenerate list of next buses on every request

Refs #1
Update badge on selecting another schedule

Refs #1
Fixes #1
Merge pull request #2 from alexeykuzmin/issue-1

Minimize localStorage usage and update rate
Update README.md
New version: refactored by alexeykuzmin