Add timezone settings under general settings

[CeciliaHinga]

Which user group(s) are the primary audience for this feature/enhancement.
Ushahidi.io Users

Is your feature request related to a problem? Please describe.
Submitted posts display time based on each person's timezone, meaning you will see a report's post time based on the local time that your computer was set in.

Describe the solution you'd like
Add timezone settings to have a deployment display one timezone for everybody who views that deployment.

Aha! Link: https://ushahiditeam.aha.io/features/PROD-902