Implement support for SSM parameter store

This commit adds initial support for the Simple System Manager client.

It currently only mocks the following api endpoints:
 - delete_parameter()
 - put_parameter()
 - get_parameters()

tests/test_ssm/test_ssm_boto3.py

@@ -0,0 +1,114 @@
+from __future__ import unicode_literals
+
+import boto3
+import sure   # noqa
+
+from moto import mock_ssm
+
+
+@mock_ssm
+def test_delete_parameter():
+    client = boto3.client('ssm', region_name='us-east-1')
+
+    client.put_parameter(
+        Name='test',
+        Description='A test parameter',
+        Value='value',
+        Type='String')
+
+    response = client.get_parameters(Names=['test'])
+    len(response['Parameters']).should.equal(1)
+
+    client.delete_parameter(Name='test')
+
+    response = client.get_parameters(Names=['test'])
+    len(response['Parameters']).should.equal(0)
+
+
+@mock_ssm
+def test_put_parameter():
+    client = boto3.client('ssm', region_name='us-east-1')
+
+    client.put_parameter(
+        Name='test',
+        Description='A test parameter',
+        Value='value',
+        Type='String')
+
+    response = client.get_parameters(
+        Names=[
+            'test'
+        ],
+        WithDecryption=False)
+
+    len(response['Parameters']).should.equal(1)
+    response['Parameters'][0]['Name'].should.equal('test')
+    response['Parameters'][0]['Value'].should.equal('value')
+    response['Parameters'][0]['Type'].should.equal('String')
+
+
+@mock_ssm
+def test_put_parameter_secure_default_kms():
+    client = boto3.client('ssm', region_name='us-east-1')
+
+    client.put_parameter(
+        Name='test',
+        Description='A test parameter',
+        Value='value',
+        Type='SecureString')
+
+    response = client.get_parameters(
+        Names=[
+            'test'
+        ],
+        WithDecryption=False)
+
+    len(response['Parameters']).should.equal(1)
+    response['Parameters'][0]['Name'].should.equal('test')
+    response['Parameters'][0]['Value'].should.equal('kms:default:value')
+    response['Parameters'][0]['Type'].should.equal('SecureString')
+
+    response = client.get_parameters(
+        Names=[
+            'test'
+        ],
+        WithDecryption=True)
+
+    len(response['Parameters']).should.equal(1)
+    response['Parameters'][0]['Name'].should.equal('test')
+    response['Parameters'][0]['Value'].should.equal('value')
+    response['Parameters'][0]['Type'].should.equal('SecureString')
+
+
+@mock_ssm
+def test_put_parameter_secure_custom_kms():
+    client = boto3.client('ssm', region_name='us-east-1')
+
+    client.put_parameter(
+        Name='test',
+        Description='A test parameter',
+        Value='value',
+        Type='SecureString',
+        KeyId='foo')
+
+    response = client.get_parameters(
+        Names=[
+            'test'
+        ],
+        WithDecryption=False)
+
+    len(response['Parameters']).should.equal(1)
+    response['Parameters'][0]['Name'].should.equal('test')
+    response['Parameters'][0]['Value'].should.equal('kms:foo:value')
+    response['Parameters'][0]['Type'].should.equal('SecureString')
+
+    response = client.get_parameters(
+        Names=[
+            'test'
+        ],
+        WithDecryption=True)
+
+    len(response['Parameters']).should.equal(1)
+    response['Parameters'][0]['Name'].should.equal('test')
+    response['Parameters'][0]['Value'].should.equal('value')
+    response['Parameters'][0]['Type'].should.equal('SecureString')