Fixed zipping at release.bash

Before, we zipped the src folder, but addons.firefox.org doesn't like
having the src folder zipped; instead, it only wants its contents
zipped.

This commit fixes this issue.

Change-Id: I605ad8abe9975dc120fa84f32255a19a1921ab92
diff --git a/release.bash b/release.bash
index 311d6c6..6b8851e 100644
--- a/release.bash
+++ b/release.bash
@@ -86,7 +86,7 @@
 # Create ZIP file for upload to the Chrome Web Store
 mkdir -p out
 rm -rf out/twpowertools-$version-$browser-$channel.zip
-zip -rq out/twpowertools-$version-$browser-$channel.zip src -x *.git*
+(cd src && zip -rq ../out/twpowertools-$version-$browser-$channel.zip * -x *.git*)
 
 # Clean generated manifest.json file
 rm -f src/manifest.json