Market, New Posting, and Existing Posting Pages

New Posting page:
-Added js to handle action of adding a new book (button click)
-CSS additions/modifications
-Added AddBook partial view for entering new book information
-Corrected passing of MarketPostModel to TextBook under
PostingController
Market page:
-Moved search button inside PostContainer
-CSS additions/modifications
Existing Posting page:
-Moved search button inside PostContainer