This is a Blank OS X App Bundle that runs Script.sh contained in the Contents/MacOS folder. I created it just compiling a Blank Cocoa application in XCode and editing Info.plis to suit my needs.
Just edit Script.sh inside Contents/MacOS.
To add an icon it must be in ICNS format. First of all you have to copy it in Contents/Resources, then you have to add a new key to Info.plist this way:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<!-- Lots of stuff
~~~~~~~~~~
~~~~~~~
~~~~~~~~~
~~~~~~~~~~
-->
<!-- And now your icon stuff -->
<key>CFBundleIconFiles</key>
<string>MySuperCoolIcon.icns</string>
<!-- That's all folks! -->
</dict>
</plist>
Feel free to ask me!