add MANIFEST.in to ensure source distribution contains all required files
Except tests as they are too big...
diff --git a/MANIFEST.in b/MANIFEST.in
new file mode 100644
index 0000000..179bc6e
--- /dev/null
+++ b/MANIFEST.in
@@ -0,0 +1,18 @@
+include CONTRIBUTING.md
+include dec/*.c
+include dec/*.h
+include dec/Makefile
+include enc/*.cc
+include enc/*.h
+include enc/Makefile
+include LICENSE
+include MANIFEST.in
+include python/bro.py
+include python/brotlimodule.cc
+include python/README.md
+include README.md
+include setup.py
+include shared.mk
+include tools/bro.cc
+include tools/Makefile
+include tools/version.h
\ No newline at end of file