[gnome-build-meta] Removing revisioned project.refs, and set to .gitignore

[Tristan Van Berkom <tvb src gnome org>]

commit 7b7557e7ba9dc972137ae26da817ed5f7abf2562
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Thu Mar 22 01:58:16 2018 +0900

    Removing revisioned project.refs, and set to .gitignore
    
    This simplifies workflow, and the cost is that things are
    a little bit slower the first time you run `bst track` or
    `bst build --track-all`.

 .gitignore   |   3 ++
 project.refs | 101 -----------------------------------------------------------
 2 files changed, 3 insertions(+), 101 deletions(-)
---
diff --git a/.gitignore b/.gitignore
index 72f9ee2..7890e3e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
 # Ignore buildstream local state
 .bst
+
+# Never commit project.refs
+project.refs