Make replying to SMS work

Summary:
 - Made toggling `Reply` link work.
 - Updated the location request canned message to something more meaningful.

*TODO:*
Clicking on the Send button doesn't work. Will fix this in subsequent diff updates.
On `#messages/list/all` page load, you've to click on the `Reply` link twice before the response form shows up. Really not sure why this behaviour. Need to investigate.

Test Plan:
- Go to #messages/list/all
- Click on `Reply` link
- See response form display
- Click on `location` button
- See a message initialized in the textarea
- Click on `more info` button
- See a message initialized in the textarea
- Click `Send` button
- See the message in the textarea sent as SMS

Reviewers: shadowhand, rjmackay

Reviewed By: shadowhand, rjmackay

Subscribers: seth, srutto, lkamau

Maniphest Tasks: T451, T439

Differential Revision: https://phabricator.ushahidi.com/D211