[EC2] Add default history server port to ec2 script

Right now I have to open it manually

Author: Andrew Or <andrewor14@gmail.com>

Closes #1296 from andrewor14/hist-serv-port and squashes the following commits:

8895a1f [Andrew Or] Add default history server port to ec2 script
(cherry picked from commit 56e009d4f05d990c60e109838fa70457f97f44aa)

Conflicts:

	ec2/spark_ec2.py