login page auto-focus on username field

As described in ticket: https://issues.apache.org/jira/browse/COUCHDB-2373

Small thing, but it was bugging me. :)
haha oops, sorry! I didn't know you guys prefered that. And yeah, agreed - a style guide for stuff like this would be brilliant. I've seen inconsistent usages around the code, so I picked one and went with it. Go figure it was the wrong one. I'll include spaces after function names from here on out. :)