Add float and percent types for FieldAttributes

Also sets the max_fail_percentage value to the percent type.

lib/ansible/playbook/base.py

@@ -289,8 +289,16 @@ class Base:
                         value = unicode(value)
                     elif attribute.isa == 'int':
                         value = int(value)
+                    elif attribute.isa == 'float':
+                        value = float(value)
                     elif attribute.isa == 'bool':
                         value = boolean(value)
+                    elif attribute.isa == 'percent':
+                        # special value, which may be an integer or float
+                        # with an optional '%' at the end
+                        if isinstance(value, string_types) and '%' in value:
+                            value = value.replace('%', '')
+                        value = float(value)
                     elif attribute.isa == 'list':
                         if value is None:
                             value = []

lib/ansible/playbook/play.py

@@ -78,7 +78,7 @@ class Play(Base, Taggable, Become):
     # Flag/Setting Attributes
     _any_errors_fatal    = FieldAttribute(isa='bool', default=False)
     _force_handlers      = FieldAttribute(isa='bool')
-    _max_fail_percentage = FieldAttribute(isa='string', default='0')
+    _max_fail_percentage = FieldAttribute(isa='percent')
     _serial              = FieldAttribute(isa='int', default=0)
     _strategy            = FieldAttribute(isa='string', default='linear')