Add basic support for custom fields

Custom fields (text, number, date, list, checkbox) may be read and set
for each card.

trello/board.py

@@ -8,6 +8,7 @@
 from trello.trellolist import List
 from trello.label import Label
 from trello.checklist import Checklist
+from trello.customfield import CustomFieldDefinition
 from dateutil import parser as dateparser
 
 
@@ -38,6 +39,7 @@ def __init__(self, client=None, board_id=None, organization=None, name=''):
 		self.id = board_id
 		self.name = name
 		self.date_last_activity = self.get_last_activity()
+		self.customFieldDefinitions = None
 
 	@classmethod
 	def from_json(cls, trello_client=None, organization=None, json_obj=None):
@@ -75,6 +77,7 @@ def fetch(self):
 		self.description = json_obj.get('desc', '')
 		self.closed = json_obj['closed']
 		self.url = json_obj['url']
+		self.customFieldDefinitions = None
 
 	# Saves a Trello Board
 	def save(self):
@@ -168,6 +171,16 @@ def list_lists(self, list_filter='all'):
 		"""
 		return self.get_lists(list_filter=list_filter)
 
+	def get_custom_field_definitions(self):
+		"""Get all custom field definitions for this board
+
+		:rtype: list of CustomFieldDefinition
+		"""
+		if self.customFieldDefinitions is None:
+			json_obj = self.client.fetch_json('/boards/' + self.id + '/customFields')
+			self.customFieldDefinitions = CustomFieldDefinition.from_json_list(self, json_obj)
+		return self.customFieldDefinitions
+
 	def get_labels(self, fields='all', limit=50):
 		"""Get label
 

trello/card.py

@@ -12,6 +12,7 @@
 from trello.compat import force_str
 from trello.label import Label
 from trello.organization import Organization
+from trello.customfield import CustomField
 
 
 class Card(TrelloBase):
@@ -153,6 +154,7 @@ def from_json(cls, parent, json_obj):
         card.idBoard = json_obj['idBoard']
         card.idList = json_obj['idList']
         card.idShort = json_obj['idShort']
+        card.customFields = CustomField.from_json_list(card, json_obj['customFieldItems'])
         card.labels = Label.from_json_list(card.board, json_obj['labels'])
         card.dateLastActivity = dateparser.parse(json_obj['dateLastActivity'])
         if "attachments" in json_obj:
@@ -174,7 +176,7 @@ def fetch(self, eager=True):
         """
         json_obj = self.client.fetch_json(
             '/cards/' + self.id,
-            query_params={'badges': False})
+            query_params={'badges': False, 'customFieldItems': 'true'})
         self.id = json_obj['id']
         self.name = json_obj['name']
         self.desc = json_obj.get('desc', '')
@@ -186,6 +188,7 @@ def fetch(self, eager=True):
         self.idList = json_obj['idList']
         self.idBoard = json_obj['idBoard']
         self.idLabels = json_obj['idLabels']
+        self.customFields = CustomField.from_json_list(self, json_obj['customFieldItems'])
         self.labels = Label.from_json_list(self.board, json_obj['labels'])
         self.badges = json_obj['badges']
         self.pos = json_obj['pos']