Change pull-local to just be a wrapper for pull with file:///

This follows up from the previous commit; now that pull knows how to
do the efficient link() or copy for local files, we can just have
pull-local call into ostree_repo_pull().

As part of this:
 - pull() can also accept a file:/// URI instead
   of a remote name (since pull local supports anonymous pulls)
 - pull() knows an "override-remote-name" option, since pull-local
   supported writing a ref out even if there wasn't a remote with
   that name

src/libostree/ostree-repo.c

@@ -231,6 +231,12 @@ ost_repo_remove_remote (OstreeRepo   *self,
   return removed;
 }
 
+gboolean
+_ostree_repo_remote_name_is_file (const char *remote_name)
+{
+  return g_str_has_prefix (remote_name, "file://");
+}
+
 gboolean
 _ostree_repo_get_remote_option (OstreeRepo  *self,
                                 const char  *remote_name,
@@ -242,6 +248,12 @@ _ostree_repo_get_remote_option (OstreeRepo  *self,
   local_cleanup_remote OstreeRemote *remote = NULL;
   gboolean ret = FALSE;
 
+  if (_ostree_repo_remote_name_is_file (remote_name))
+    {
+      *out_value = g_strdup (default_value);
+      return TRUE;
+    }
+
   remote = ost_repo_get_remote (self, remote_name, error);
 
   if (remote != NULL)
@@ -267,6 +279,12 @@ _ostree_repo_get_remote_list_option (OstreeRepo   *self,
   local_cleanup_remote OstreeRemote *remote = NULL;
   gboolean ret = FALSE;
 
+  if (_ostree_repo_remote_name_is_file (remote_name))
+    {
+      *out_value = NULL;
+      return TRUE;
+    }
+
   remote = ost_repo_get_remote (self, remote_name, error);
 
   if (remote != NULL)
@@ -304,6 +322,12 @@ _ostree_repo_get_remote_boolean_option (OstreeRepo  *self,
   local_cleanup_remote OstreeRemote *remote = NULL;
   gboolean ret = FALSE;
 
+  if (_ostree_repo_remote_name_is_file (remote_name))
+    {
+      *out_value = default_value;
+      return TRUE;
+    }
+  
   remote = ost_repo_get_remote (self, remote_name, error);
 
   if (remote != NULL)