[SPARK-4983] Insert waiting time before tagging EC2 instances

The boto API doesn't support tag EC2 instances in the same call that launches them.
We add a five-second wait so EC2 has enough time to propagate the information so that
the tagging can succeed.

Author: GenTang <gen.tang86@gmail.com>
Author: Gen TANG <gen.tang86@gmail.com>

Closes #3986 from GenTang/spark-4983 and squashes the following commits:

13e257d [Gen TANG] modification of comments
47f06755 [GenTang] print the information
ab7a931 [GenTang] solve the issus spark-4983 by inserting waiting time
3179737 [GenTang] Revert "handling exceptions about adding tags to ec2"
6a8b53b [GenTang] Revert "the improvement of exception handling"
13e97a6 [GenTang] Revert "typo"
63fd360 [GenTang] typo
692fc2b [GenTang] the improvement of exception handling
6adcf6d [GenTang] handling exceptions about adding tags to ec2