[Torquebox4] Fix gemfile path

Bundler sets `ENV['BUNDLE_GEMFILE']` variable to application's root gemfile. That leads to problems like in #184.

Second commit fixes problem #186. This is impossible to simply copy `gemspec` to tmpdir because it won't work without app files. So I think the simplest approach is to copy the whole app.

In addition it will partially fix the situation if there are deps with relative paths  `gem 'gemname', path: 'gemname/'`.
But this won't help if path leads to upper directory like that `gem 'gemname', path: '../core'`.