US4: Set up backend event handling and controllers for resolve button clicks

[cathyxfeiyang]

Depends on #45 , #47 , #48
Acceptance criteria:

• Visually test that clicking the resolve button sets the resolve status of the topic to resolved, and the resolve button is disabled
• Automated testing to verify that a topic's resolve field is set to 1 after calling resolve with appropriate privileges
• Automated testing to verify that a topic's resolve field is not changed after calling resolve with inappropriate privileges