Add c3 instance types to Spark EC2

The number of disks for the c3 instance types taken from here: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html#StorageOnInstanceTypes

Author: Christian Lundgren <christian.lundgren@gameanalytics.com>

Closes #595 from chrisavl/branch-0.9 and squashes the following commits:

c8af5f9 [Christian Lundgren] Add c3 instance types to Spark EC2
(cherry picked from commit 19b4bb2b444f1dbc4592bf3d58b17652e0ae6d6b)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
Merge pull request #598 from shivaram/master.

Update spark_ec2 to use 0.9.0 by default

Backports change from branch-0.9

Author: Shivaram Venkataraman <shivaram@eecs.berkeley.edu>

Closes #598 and squashes the following commits:

f6d3ed0 [Shivaram Venkataraman] Update spark_ec2 to use 0.9.0 by default Backports change from branch-0.9
Typo: Standlone -> Standalone

Author: Andrew Ash <andrew@andrewash.com>

Closes #601 from ash211/typo and squashes the following commits:

9cd43ac [Andrew Ash] Change docs references to metrics.properties, not metrics.conf
3813ff1 [Andrew Ash] Typo: mulitcast -> multicast
873bd2f [Andrew Ash] Typo: Standlone -> Standalone