Fixing AWS instance type information based upon current EC2 data

Fixed a problem in previous file in which some information regarding AWS instance types were wrong. Such information was updated base upon current AWS EC2 data.

Author: Zichuan Ye <jerry@tangentds.com>

Closes #1156 from jerry86/master and squashes the following commits:

ff36e95 [Zichuan Ye] Fixing AWS instance type information based upon current EC2 data
(cherry picked from commit 62d4a0fa9947e64c1533f66ae577557bcfb271c9)

Conflicts:

	ec2/spark_ec2.py