feature: adding date variables, including a custom medium date

## Ready State: (Yes)

This pull request is related to the following JIRA tickets: [LDC-230 Create panelized news article display page](https://imagex.atlassian.net/browse/LDC-230).

## Requirements & Dependencies


## Deployment Instructions

* Merge code.
* Enable module `imagex_user`: `drush en imagex_user`
* Clear caches with `drush cc all`

## Usage/Test Instructions

* User entity should have an profile image field and if panels is enabled, panelizer settings should be set.