Some maniphest / aphront form UI tweaks

Summary:
Just a few random things I wanted to tweak...

• Maniphest homepage tasks box has less padding so it vertically aligns with other "stuff" boxes
• Made form <h1> have more padding

Test Plan:

• Looked at Maniphest on the homepage -- looks good!
• Looked at Maniphest Task List
• " Batch Edit
• Looked at a view other form places like Herald rules and Repository edit - looks good

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1776