Bundler binstubs not always generated

[roback]

The fix we did in e099d55 fixed something, but I think it also broke another step of the deploy.

I tried deploying a new application and ran into #63. I added the workaround mentioned in that issue, but the deploy still failed.

Turns out the binstubs weren't generated, and in order to get them to generate I also had to add

set :bundle_binstubs, -> { shared_path.join('bin') }
set :bundle_check_before_install, false # From the issue mentioned above

to the config/deploy.rb file. This to ensure the --binstubs flag gets added to the bundle install command in capistrano-bundler in the followin place (It's linked in the above mentioned issue too).