Facebook feed full images size

Problem/Motivation

Have the option to choose a full size image

Steps to reproduce

Configured Facebook (/admin/config/socialfeed/facebook)
Add the facebook block on the website pages
the thumbnail images too small.

Proposed resolution

1. Have option to request the full picture from Facebook API (fields 'picture' or 'full_picture').
2. Add the field full_picture to fields list when requesting data from Facebook API - developer will have the option to use in in custom template. (currently requesting only: 'permalink_url','message','created_time','picture','status_type')

Remaining tasks

User interface changes

API changes

Data model changes