Python Vs Ruby On Rails : on Size
I don't think you can get them both. I'm sorry to say this but you have to choose which one is more important to you. 

Django application is smaller in size because many things is already provided out of the box, but deployment is not as easy.
On the other hand, RoR apps deployment is easier (both Ruby MRI or JRuby) but the application's size is naturally larger given you have to install other gems and Ruby On Rails plugins.
I am planning to do a small web application that will be distributed as a single installable. I have plans to develop this application in either Python/Django or Ruby On Rails. (I am a Java/C++ programmer, hence both these languages are new to me). 
My main concern is about the size and simplicity of final installable (say setup.exe). I want it to be small in size and also should be able to pack all required components in it. 
Which one among Python/Django and Ruby On Rails is suitable for me?