[SPARK-8482] Added M4 instances to the list.

AWS recently added M4 instances (https://aws.amazon.com/blogs/aws/the-new-m4-instance-type-bonus-price-reduction-on-m3-c4/).

Author: Pradeep Chhetri <pradeep.chhetri89@gmail.com>

Closes #6899 from pradeepchhetri/master and squashes the following commits:

4f4ea79 [Pradeep Chhetri] Added t2.large instance
3d2bb6c [Pradeep Chhetri] Added M4 instances to the list

ec2/spark_ec2.py

@@ -362,7 +362,7 @@ def get_validate_spark_version(version, repo):
 
 
 # Source: http://aws.amazon.com/amazon-linux-ami/instance-type-matrix/
-# Last Updated: 2015-05-08
+# Last Updated: 2015-06-19
 # For easy maintainability, please keep this manually-inputted dictionary sorted by key.
 EC2_INSTANCE_TYPES = {
     "c1.medium":   "pvm",
@@ -404,6 +404,11 @@ EC2_INSTANCE_TYPES = {
     "m3.large":    "hvm",
     "m3.xlarge":   "hvm",
     "m3.2xlarge":  "hvm",
+    "m4.large":    "hvm",
+    "m4.xlarge":   "hvm",
+    "m4.2xlarge":  "hvm",
+    "m4.4xlarge":  "hvm",
+    "m4.10xlarge": "hvm",
     "r3.large":    "hvm",
     "r3.xlarge":   "hvm",
     "r3.2xlarge":  "hvm",
@@ -413,6 +418,7 @@ EC2_INSTANCE_TYPES = {
     "t2.micro":    "hvm",
     "t2.small":    "hvm",
     "t2.medium":   "hvm",
+    "t2.large":    "hvm",
 }
 
 
@@ -923,7 +929,7 @@ def wait_for_cluster_state(conn, opts, cluster_instances, cluster_state):
 # Get number of local disks available for a given EC2 instance type.
 def get_num_disks(instance_type):
     # Source: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html
-    # Last Updated: 2015-05-08
+    # Last Updated: 2015-06-19
     # For easy maintainability, please keep this manually-inputted dictionary sorted by key.
     disks_by_instance = {
         "c1.medium":   1,
@@ -965,6 +971,11 @@ def get_num_disks(instance_type):
         "m3.large":    1,
         "m3.xlarge":   2,
         "m3.2xlarge":  2,
+        "m4.large":    0,
+        "m4.xlarge":   0,
+        "m4.2xlarge":  0,
+        "m4.4xlarge":  0,
+        "m4.10xlarge": 0,
         "r3.large":    1,
         "r3.xlarge":   1,
         "r3.2xlarge":  1,
@@ -974,6 +985,7 @@ def get_num_disks(instance_type):
         "t2.micro":    0,
         "t2.small":    0,
         "t2.medium":   0,
+        "t2.large":    0,
     }
     if instance_type in disks_by_instance:
         return disks_by_instance[instance_type]