Merge pull request #1330 from hypothesis/search-visibility-quirks

Fix quirks with show/hide on the search bar
Fix regression: broken view sort

Bad tag nesting killed the styles.
Introduced in ae0919804627a2963c63c48f0a96761bd91faec4.
Handle all 404s with the application

Close #1336
Use asset specs for all template references

This makes it possible to override them using Pyramid's
`config.override_asset` API.
Merge pull request #1337 from hypothesis/overridable-templates

Use asset specs for all template references
Turn the standalone page into the app

Close #427
Close #754
Remove obsoleted displayer.pt template