Remove executable from python files which don't really needs it

Additionally fix length of the line in api/base.py file to fit 79 line
chars limit.

TrivialFix

Change-Id: I37253f28cbbddf58740d7f75cad6ee7cc9be8954
diff --git a/doc/source/conf.py b/doc/source/conf.py
old mode 100755
new mode 100644
diff --git a/neutron_tempest_plugin/api/base.py b/neutron_tempest_plugin/api/base.py
index b659637..7f056d1 100644
--- a/neutron_tempest_plugin/api/base.py
+++ b/neutron_tempest_plugin/api/base.py
@@ -531,7 +531,7 @@
 
     @classmethod
     def reserve_subnet_cidr(cls, addr, **ipnetwork_kwargs):
-        """Reserve given subnet CIDR making sure it is not used by create_subnet
+        """Reserve given subnet CIDR making sure it's not used by create_subnet
 
         :param addr: the CIDR address to be reserved
         It can be a str or netaddr.IPNetwork instance