Whenever I do bundle install all of the gems get installed at
app_dir/vendor/bundle
path and consumes loads of disk space. I a
First of all, acording to your info, it seems that you have installed both rvm and rbenv. Thats a very bad idea. You have to delete one of them (rbenv + bundler works like a charm for me, didnt try rvm).
In regard to your question check .bundle/config in your project, as all the configuration for bundle to that project lies there (if its still deleted, you can create a new one). You migh want to add this line (or change it, if its already there): BUNDLE_DISABLE_SHARED_GEMS: '0' for sharing gems, they go where your BUNDLE_PATH: is set (BUNDLE_PATH: vendor in my case).
For the global configuration file look in ~/.bundle/config
Also this man page could be of use: bundle config