Clean up some dialog spacing

Summary: Makes dialogs a little wider, form dialogs a lot wider (space controls). Also cleans up Passphrase dialogs. Fixes T12833. I think forms probably need to move to tables for better layout flexibility like veritical alignment.

Test Plan: Passphrase create, edit, etc. Other dialogs.

Reviewers: epriestley

Subscribers: Korvin

Maniphest Tasks: T12833

Differential Revision: https://secure.phabricator.com/D18382