First prototype

The prototype should be functional, although there might be some bugs.
It should be able to retrieve a list of thread IDs in a Google Group,
and use it to download all the whole threads as returned by the server
(in pb+json format).

Change-Id: I434321a2db96a6e983d27b69b86efd5abebe7618
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..61065af
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+threads/
+threads.txt