Tweaks to CSS for search button symmetry, cleaner alignment.  Show unavailable videos to admins.

Title says it all.  In chrome, search button is asymmetric / not quite aligned.  Tweaked to fit chrome, no idea how it appears on other browsers.

I re-tweaked search to show unavailable videos to admins, as search can be an easy way to find what videos are available, and at what paths in the topic tree they exist.

Before (all effects are only slightly off): button margin asymmetric, not aligned with textbox, and not aligned with other navbar text
![image](https://f.cloud.github.com/assets/4072455/1650628/7bcfbef4-5a9e-11e3-9ab9-3fafdf0607ed.png)

Current (chrome only!)
![screen shot 2013-12-01 at 7 28 24 am](https://f.cloud.github.com/assets/4072455/1650626/5883735a-5a9e-11e3-84c9-6500105cbb60.png)

@jamalex Would like to run by you, both to get your thoughts (since these are tweaks on your tweaks) and to see if you could test on the android tablets (I don't have any at home)