update about trends

[baozi10tech]

1. changed the name of index.js to trends.js. So that we could build a trigger.js and don't have to write too much code in one js script
2. add a summary pie chart
3. improved line chart by including x, y axes labels, titles and removing shade area
4. Tried to change the 24-hour format to 12-hour format. One concern is the time might has to be precise to seconds. So I leave it unchanged. We can talk about it....
5. add alert when no data is found at a date Thank you!