Update configuration item names in template

The template core module allows users to set configuration items in two
ways, either through the `astropy` configuration system or through class
or instance attributes. The attribute names are no longer in capital
letters because the convention is to reserve such names for constants,
and the configuration item names now match the attribute names.

astroquery/template_module/__init__.py

@@ -18,7 +18,7 @@ class Conf(_config.ConfigNamespace):
     """
     Configuration parameters for `astroquery.template_module`.
     """
-    server = _config.ConfigItem(
+    url = _config.ConfigItem(
         ['http://dummy_server_mirror_1',
          'http://dummy_server_mirror_2',
          'http://dummy_server_mirror_n'],

astroquery/template_module/core.py

@@ -45,16 +45,16 @@ class TemplateClass(BaseQuery):
     # The private properties defined here allow the users to change the
     # configuration values at runtime, or to completely override them with
     # instance attributes.
-    URL = ''          # A falsy default that cannot be mistaken for a valid value.
-    TIMEOUT = None    # Use `None` if the falsy value could be valid.
+    url = ''          # A falsy default that cannot be mistaken for a valid value.
+    timeout = None    # Use `None` if the falsy value could be valid.
 
     @property
     def _url(self):
-        return self.URL or conf.server
+        return self.url or conf.url
 
     @property
     def _timeout(self):
-        return conf.timeout if self.TIMEOUT is None else self.TIMEOUT
+        return conf.timeout if self.timeout is None else self.timeout
 
     # all query methods are implemented with an "async" method that handles
     # making the actual HTTP request and returns the raw HTTP response, which