cleanup the feed page menu

[shizunge]

Today we use the same menu in the feeds page and the add-new-feed page.
There are 5 items now:

1. Feeds
2. Add new feed
3. Export
4. Import
5. Refresh all

I do not think the first item "feeds" is useful in the feed page. And items 2-5 are useful in the add-new-feed page.

We probably should not share the menu between the two pages. Instead, we show only item 2-5 in the feeds page, and only item 1 in the add-new-feed page.

This looks like how we do for the category and add-new-category page. In the menu of the category page there is only 1 item "add new category". In the menu of the add-new-category page, there is 1 item "categories".