solved issue 80.
 80) check that API_MAX_TEXT_LENGTHS constant is used for all api's
     make generic singleton method to split direction + description + deep link into 1-3 fields.
     facebook: 1 field message (47950)
     flckr: 2 fields title (255) and description (nil)
     linkedin: 3 fields title (200), description (256) and comment (700)
   ( twitter: 1 field tweet (140) with special rules for link and picture
     vkontakte: 1 field caption (255)
     added get_wall_post_text_fields and self.test_get_wall_post_text_fields to ApiGift
     changed post in api wall methods to use get_wall_post_text_fields