Add OWNERS files

Also, change the release.bash script so it doesn't include the OWNERS
file in the release ZIP (nor the .DS_Store files).

Change-Id: I09fc621838714f0620a3efb3a3e4824d9ee60258
diff --git a/release.bash b/release.bash
index a18d51b..75ac4aa 100644
--- a/release.bash
+++ b/release.bash
@@ -102,7 +102,8 @@
 mkdir -p out
 rm -rf out/twpowertools-$version-$browser-$channel.zip
 (cd src &&
-  zip -rq ../out/twpowertools-$version-$browser-$channel.zip * -x *.git*)
+  zip -rq ../out/twpowertools-$version-$browser-$channel.zip * -x "*/.git*" \
+  -x "*/\.DS_Store" -x "*/OWNERS")
 
 # Clean generated manifest.json file
 rm -f src/manifest.json