Some cleanups on code dropped by Evernote

So no possibility of conflict when picking.
Remove superfluous blank line
Remove unused import
More cleanups on code dropped by Evernote

So no possibility of conflict when picking.
Docs: remove blank space before newline
Added terminology dependency to cache tag (this fixes evernote#1)

Conflicts:
	pootle/templates/editor/units/edit.html
Partial pick: Updated the entire base.html template from the override one

Some of the changes are not interesting for us.
Other changes were undone in:

- evernote/pootle@373fbfb9
- evernote/pootle@933b03f1
- evernote/pootle@6bb67a86

and to avoid picking extra commits we just pick here the commits that are
not undone and that are insteresting for us.

Conflicts:
	pootle/templates/layout.html
Under Windows, locale names are different and setlocale() with regular locale names will fail; so just set the default locale and quit early. This will avoid polluting the logs with numerous 'Failed to set locale' debug messages

Conflicts:
	pootle/middleware/setlocale.py
Cleaner and flattier buttton shadows
Removed extra charset declaration
Fix number formatting crash under Windows
Cleanup: coding style fix
Reuse existing code

Picking this required extensive changes due to the huge differences between
Evernote code and our code in this specific view.

Conflicts:
	pootle/apps/pootle_translationproject/views.py
Ignore empty path parts
Revert to previous behaviour
Added creation_time field to Unit

Pick note: Changed name of the migration to keep the numbering.
Check for permissions by using the decorator
Point to the editor URL

Conflicts:
	pootle/apps/pootle_statistics/models.py
Unified units query

Conflicts:
	pootle/apps/pootle_store/models.py
Singularize permission checking

Views only check a single permission at a time.

Conflicts:
	pootle/core/decorators.py