Save and display timezone in the date/date-time field in posts

[Angamanga]

Background

The date and date-time fields information in posts are converted and saved as a date-time field without any information about the timezone it was added in. This means that if another timezone than UTC was used when adding the post, the time when displaying the post will be confusing to the user.

Expected behaviour/TODO

• Continue saving the information in UTC but add a column in the database with the timezone information
• Return timezone information when requesting the post_datetime field
• Display the time in posts adjusted to the timezone-settings in the users computer
• Add a toggle in the post to display the time in the timezone that was used when adding the post
• Clearly show what timezone times are displayed in.
• Clearly show if we lack the original timezone (for example for posts added before this change)

Aha! Link: https://ushahiditeam.aha.io/features/PROD-905