Implement search bar in mainPage

[ashx3s]

The last discussed mockusps in pagure.io/design/issues/715 featured a large search bar with filters at the top. It would be good to implement this.

While there isn't visual hierarchy in the mockup that separates the search bar from the issues, I wanted to suggest designing the site in such a way that the search bar is always partially visible as the user scrolls through content. For this idea to not devour too much visual real estate, it should shrink up to the header a bit but still be quick for a user to get to.

[gridhead]

@lilyx13,

I would suggest having a consistent small-sized search bar on the right side of the navbar and have the sticky-like class on the navbar to have it persist throughout scrolling down as it is much easier to implement. But if you are willing to go the extra mile to ensure that the search bar is reduced progressively to the navbar - that is very appreciated!

Just be careful about taking up a lot of time into implementing the feature in this way as the visual shrinking is a "nice to have" addition and not a "necessity".