Add bit_length_power_of_2 to filters folder

We are moving this filter into this repository because it's only
usage is here. It will then be removed from openstack-ansible-plugins.

Patch set 2: Fix whitespace

Change-Id: I543328db49dc6b7bbb05878503dbb3d337a18558
Related-Bug: #1826242

filter_plugins/osa-filter.py

@@ -0,0 +1,17 @@
+def bit_length_power_of_2(value):
+    """Return the smallest power of 2 greater than a numeric value.
+    :param value: Number to find the smallest power of 2
+    :type value: ``int``
+    :returns: ``int``
+    """
+    return 2**(int(value) - 1).bit_length()
+
+
+class FilterModule(object):
+    """Ansible jinja2 filters."""
+
+    @staticmethod
+    def filters():
+        return {
+            'bit_length_power_of_2': bit_length_power_of_2
+        }