Default repo manifest settings in git config

A default manifest URL can be specified using:
  git config --global repo-manifest.<id>.url <url>

A default manifest server can be specified using:
  git config --global repo-manifest.<id>.server <url>

A default git mirror reference can be specified using:
  git config --global repo-manifest.<id>.reference <path>

This will allow the user to use 'repo init -u <id>' as
a shorter alternative to specifying the full URL.

Also, manifest server will not have to be specified in the
manifest XML and the reference will not have to be specified
on the command line. If they are, they will override these
default values however.

Change-Id: Ifdbc160bd5909ec7df9efb0c5d7136f1d9351754
Signed-off-by: Victor Boivie <victor.boivie@sonyericsson.com>
diff --git a/manifest_xml.py b/manifest_xml.py
index 9189eec..c9e5c40 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -228,7 +228,11 @@
   @property
   def manifest_server(self):
     self._Load()
-    return self._manifest_server
+
+    if self._manifest_server:
+      return self._manifest_server
+
+    return self.manifestProject.config.GetString('repo.manifest-server')
 
   @property
   def IsMirror(self):