created FacebookPostCreator class

started towards moving post creation tests out of timeline concatenator spec

added method to create 'photo' facebook posts
added method to create Facebook wall_post
it can handle facebook mobile_status_update
can handle tagged_in_post status update
handle more cases for facebook photo type posts
catch more cases for mobile_status_update
facebookPostCreator can handle photo shared_story
added handling of video posts

refactored out a couple of private methods
FacebookPostCreator can handle link type shared stories,

refactored out private method
FacebookPostCreator can handle added photos posts,

refactored private method
fixed method to count number of comments
refactoring

cleaned up code in FacebookPostCreator

extracted methods
changed if/else statements to case statements