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

ff36e95 [Zichuan Ye] Fixing AWS instance type information based upon current EC2 data

ec2/spark_ec2.py

@@ -203,6 +203,8 @@ def get_spark_shark_version(opts):
 
 # Attempt to resolve an appropriate AMI given the architecture and
 # region of the request.
+# Information regarding Amazon Linux AMI instance type was update on 2014-6-20:
+# http://aws.amazon.com/amazon-linux-ami/instance-type-matrix/
 def get_spark_ami(opts):
     instance_types = {
         "m1.small":    "pvm",
@@ -218,10 +220,12 @@ def get_spark_ami(opts):
         "cc1.4xlarge": "hvm",
         "cc2.8xlarge": "hvm",
         "cg1.4xlarge": "hvm",
-        "hs1.8xlarge": "hvm",
-        "hi1.4xlarge": "hvm",
-        "m3.xlarge":   "hvm",
-        "m3.2xlarge":  "hvm",
+        "hs1.8xlarge": "pvm",
+        "hi1.4xlarge": "pvm",
+        "m3.medium":   "pvm",
+        "m3.large":    "pvm",
+        "m3.xlarge":   "pvm",
+        "m3.2xlarge":  "pvm",
         "cr1.8xlarge": "hvm",
         "i2.xlarge":   "hvm",
         "i2.2xlarge":  "hvm",
@@ -526,7 +530,8 @@ def wait_for_cluster(conn, wait_secs, master_nodes, slave_nodes):
 
 # Get number of local disks available for a given EC2 instance type.
 def get_num_disks(instance_type):
-    # From http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?InstanceStorage.html
+    # From http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html
+    # Updated 2014-6-20
     disks_by_instance = {
         "m1.small":    1,
         "m1.medium":   1,
@@ -544,8 +549,10 @@ def get_num_disks(instance_type):
         "hs1.8xlarge": 24,
         "cr1.8xlarge": 2,
         "hi1.4xlarge": 2,
-        "m3.xlarge":   0,
-        "m3.2xlarge":  0,
+        "m3.medium":   1,
+        "m3.large":    1,
+        "m3.xlarge":   2,
+        "m3.2xlarge":  2,
         "i2.xlarge":   1,
         "i2.2xlarge":  2,
         "i2.4xlarge":  4,
@@ -559,7 +566,9 @@ def get_num_disks(instance_type):
         "r3.xlarge":   1,
         "r3.2xlarge":  1,
         "r3.4xlarge":  1,
-        "r3.8xlarge":  2
+        "r3.8xlarge":  2,
+        "g2.2xlarge":  1,
+        "t1.micro":    0
     }
     if instance_type in disks_by_instance:
         return disks_by_instance[instance_type]