api: Make site settable via configuration files.

This works much better for working with staging, since rather than
needing to tell each individual tool that you're using staging, you
just specify that along with your API (which at the moment implies
whether you should be using staging or prod).

(imported from commit c1de8e72c24f35ef2160bce5339a5f03c6e1da95)

api/humbug/__init__.py

@@ -46,7 +46,7 @@ API_VERSTRING = "/api/v1/"
 def generate_option_group(parser):
     group = optparse.OptionGroup(parser, 'API configuration')
     group.add_option('--site',
-                      default='https://humbughq.com',
+                      default=None,
                       help=optparse.SUPPRESS_HELP)
     group.add_option('--api-key',
                      action='store')
@@ -69,7 +69,7 @@ def init_from_options(options):
 class Client(object):
     def __init__(self, email=None, api_key=None, config_file=None,
                  verbose=False, retry_on_errors=True,
-                 site="https://humbughq.com", client="API"):
+                 site=None, client="API"):
         if None in (api_key, email):
             if config_file is None:
                 config_file = os.path.join(os.environ["HOME"], ".humbugrc")
@@ -83,11 +83,16 @@ class Client(object):
                 api_key = config.get("api", "key")
             if email is None:
                 email = config.get("api", "email")
+            if site is None:
+                site = config.get("api", "site", None)
 
         self.api_key = api_key
         self.email = email
         self.verbose = verbose
-        self.base_url = site
+        if site is not None:
+            self.base_url = site
+        else:
+            self.base_url = "https://humbughq.com"
         self.retry_on_errors = retry_on_errors
         self.client_name = client