Add support for list item fields
Add support for list item fields

* Added build_field_filter helper function that will add fields to the query based on their internal name or display name
* Added expand_fields argument to get_items and get_item_by_id methods, if you pass True it will return all fields, if you pass a list of field names, it will filter as such
TheBigBear/python-o365,TheBigBear/python-o365