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
Move all icon classes into separate elements

This fixes an issue on the editor form where the button styles overrode
the icon font family resulting in the display text "5 Save". By having
icons reside on separate elements we reduce the chances of styles
bleeding into each other.
Merge pull request #1338 from hypothesis/fix-editor-save-icon

Move all icon classes into separate elements
Don't catch all 404s

@aron is right. Unless this application is really going to have no
server views (or until it has no server views), we should not have
such an aggressive catch-all route.
Merge pull request #1320 from hypothesis/427-standalone-app

Turn the standalone page into the app
Remove useless Annotator source maps. Fixes #1341.
Update Annotor's PDF plugin to 9acc6554 (typed-packaging).

This change was necessary to adapt to updates of the PDF.js version
shipped with newer FF releases.

There were three small changes. Our code now works with both
the old version (currently used with Chrome) and the old version
(embedded in FF).
Merge pull request #1342 from hypothesis/1341-remove-useless-source-maps

Remove useless Annotator source maps. Fixes #1341.
Use asset spec for blocks template global
Merge pull request #1343 from hypothesis/1333-fix-pdfjs-for-ff

Update Annotor's PDF plugin to 9acc6554 (typed-packaging).
Start building up a pattern library

Starting with the form elements, the new view is available at
/dev/pattern-library and currently only shows form fields.
Move pattern library view to h.testing

This ensures that it's only loaded in development.
Add experimental form styles

These new styles include labels by default and error styles. It also
gives a little more breathing room between form elements.

The buttons now have a more consistent hover/active state without the
glossy highlight and the disabled state looks disabled.
Update the login form to trial new form styles
Use Compass for button gradients