add support for AWS Organizations

endpoints covers so far:
- create_organization
- describe_organization
- create_account
- describe_account
- list_accounts

all tests passing.
could use some advise from maintaners.

tests/test_organizations/test_organizations_utils.py

@@ -0,0 +1,26 @@
+from __future__ import unicode_literals
+
+import sure   # noqa
+import moto
+from moto.organizations import utils
+
+ORG_ID_REGEX = r'o-[a-z0-9]{%s}' % utils.ORG_ID_SIZE
+ROOT_ID_REGEX = r'r-[a-z0-9]{%s}' % utils.ROOT_ID_SIZE
+ACCOUNT_ID_REGEX = r'[0-9]{%s}' % utils.ACCOUNT_ID_SIZE
+CREATE_ACCOUNT_STATUS_ID_REGEX = r'car-[a-z0-9]{%s}' % utils.CREATE_ACCOUNT_STATUS_ID_SIZE
+
+def test_make_random_org_id():
+    org_id = utils.make_random_org_id()
+    org_id.should.match(ORG_ID_REGEX)
+
+def test_make_random_root_id():
+    org_id = utils.make_random_root_id()
+    org_id.should.match(ROOT_ID_REGEX)
+
+def test_make_random_account_id():
+    account_id = utils.make_random_account_id()
+    account_id.should.match(ACCOUNT_ID_REGEX)
+
+def test_make_random_create_account_status_id():
+    create_account_status_id = utils.make_random_create_account_status_id()
+    create_account_status_id.should.match(CREATE_ACCOUNT_STATUS_ID_REGEX)