[messaging] Fix synchronization issues

[messaging] Fix synchronization issues

Due to the delay between updating email with native C API functions and
updates of the corresponding message/thread records in the mail
database, race conditions occured in the previous implementation,
resulting in inconsitencies between thread_ids in the DB and those of
messages in JS layer. Active waits have been added to mitigate this
problems.

[Verification] tct-tizen-messaging-email pass rate: 100%

Change-Id: Ie0771ffc40e6cdee696756a8e831ae56bbe8f84d
Signed-off-by: Pawel Wasowski <p.wasowski2@samsung.com>