Improve feed stories for Maniphest and some more translations

Summary: Ref T2217. Render feed stories like "alincoln updated T123" instead of "alincoln updated this task.". Fix up some more translations.

Test Plan: Looked at feed, saw something a bit more reasonable.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2217

Differential Revision: https://secure.phabricator.com/D7108