Adds meals provided field & organisation feed

[roborourke]

This fixes some bugs and warnings that were fairly benign but also does the following:

• Adds a "Meals provided" field to the log impact form
• Displays the meals provided data on user & org profiles and in the news feed
• Normalises the news feed display across home / user and org pages eg. "hours" is actually number of people helped
• Adds a feed to the organisation pages of org contributions