Drop MANIFEST.in

Pbr generates a sensible manifest from git files and some standard files.
So MANIFEST.in is not needed by pbr.

Change-Id: If79b808f94ecf35a2cf70a6a119e70cd4a07edc6
diff --git a/MANIFEST.in b/MANIFEST.in
deleted file mode 100644
index c978a52..0000000
--- a/MANIFEST.in
+++ /dev/null
@@ -1,6 +0,0 @@
-include AUTHORS
-include ChangeLog
-exclude .gitignore
-exclude .gitreview
-
-global-exclude *.pyc