EBookClient: (bug 701260) Added async apis to connect to a DRA book.

Added e_book_client_connect_direct() and e_book_client_connect_direct_finish()
test-utils: Added argumement to the fixture closure data to open async

If a closure specifies async then the EBookClient or ECalClient will be
opened using async APIs instead of sync APIs.
EBookClient tests: Use async apis to open the client for every async test.
ECalClient tests: Use async apis to open the client for every async test.