Add missing import

pootle_store/decorators.py was missing Store import and thus caused
tracback with: NameError: global name 'Store' is not defined trying to
download a file.
Use the new parent icon in goals tab
Docs: Advertise that LDAP auth backend moved in 2.5.1 release notes
Simplify and fix path summary more

AKA Expand Details link, which was broken since 4980547.
Drop the extra AJAX request for path summary
Move the bulk of path summary code to JS

This avoids the extra database queries to calculate completion
percentages.
Cosmetic
allauth: Enable OpenID and Persona login support by default
allauth: Redesign the social account registration page
allauth: Document new features in the release notes

Also move it up in the roadmap.
allauth: docs: Document allauth/social auth support
allauth: Drop a redundant dir attribute
allauth: Disable third party authentication support by default

Support will be enabled and ready if users uncomment the apps in
INSTALLED_APPS.
Also document the allauth settings accordingly.
Fix bug introduced in c209b1ee
docs: build with warnings as errors
docs: fix broken hyperlink
docs: ignore specs/ directory when building
docs: fix location of pootle_logo.png
cleanup: no need for special Pootle db setup script

Well documented elsewhere and better scripted now.
Tests: added basic requirements file