How to troubleshoot fields

[laceysanderson]

We need to document how to troubleshoot fields.

I've started this in tripal/tripal#1604 but it needs to become formal docs.

[laceysanderson]

Some good tips of things to look at:

If your field is not saving the value that you provided in the widget:

1. Check that you have a property type defined in your field with the action set to store and the property key matching the key of your widget input element.