Fix "create a flavor" tests for strong validation

On Nova v2.1/v3 API,  the input validation of "create a flavor" API
has become more strict. As the result it does not allow " 1024 " as
ram size, and does not allow "" as flavor id.

This patch fixes the related tests for passing these tests.

Change-Id: I58a8cc8fd89a12495ed995e06dbd396a82f6ec71
Closes-Bug: #1336173
diff --git a/tempest/api/compute/v3/admin/test_flavors.py b/tempest/api/compute/v3/admin/test_flavors.py
index 8a4e3cf..09d76b8 100644
--- a/tempest/api/compute/v3/admin/test_flavors.py
+++ b/tempest/api/compute/v3/admin/test_flavors.py
@@ -294,7 +294,7 @@
         flavor_name = data_utils.rand_name(self.flavor_name_prefix)
         new_flavor_id = data_utils.rand_int_id(start=1000)
 
-        ram = " 1024 "
+        ram = "1024"
         resp, flavor = self.client.create_flavor(flavor_name,
                                                  ram, self.vcpus,
                                                  self.disk,
diff --git a/tempest/api/compute/v3/admin/test_flavors_negative.py b/tempest/api/compute/v3/admin/test_flavors_negative.py
index 3f8a2da..6d3308e 100644
--- a/tempest/api/compute/v3/admin/test_flavors_negative.py
+++ b/tempest/api/compute/v3/admin/test_flavors_negative.py
@@ -57,7 +57,7 @@
         resp, flavor = self.client.create_flavor(flavor_name,
                                                  self.ram,
                                                  self.vcpus, self.disk,
-                                                 '',
+                                                 None,
                                                  ephemeral=self.ephemeral,
                                                  swap=self.swap,
                                                  rxtx=self.rxtx)