Misc. edits ahead of may release

[maxturer]

This fixes issue #545 as well as several unticketed issues.
Includes:

• fix for issue where when logged in, search bar displays "all" even when other options are selected
• fix for issue where when other options in search bar are selected, search bar resizes itself
• HTML titles given to advanced search, search results, and a few static pages
• login page redesigned and reordered
• red "x" removed from start over button on dashboard
• content edits to "share your work" page based on ScholComm feedback
• fix for issue where default "collection" icon not displayed in certain situations (see Files without thumbnails result in broken links #533)

If I missed anything minor that we want before the release (or if I should change titles on dashboard pages that don't have them, either), let me know, because this is a good branch to add those to.

[dolsysmith]

I really like the new login page! And everything else works as expected, with the caveat that I can't replicate the issue with collection-level thumbnails on my dev server...

[maxturer]

Great! I'll go ahead and merge.
Also, it's definitely not clear what triggers the no-thumbnail bug, but I've sometimes been able to trigger it by filling a new collection with works that have no associated files (sometimes, frustratingly, but not every time).