Log Message:
Update ruby-bundler package to 1.0.18.

## 1.0.18 (Aug 16, 2011)

Bugfixes:

  - Fix typo in DEBUG_RESOLVER (@geemus)
  - Fixes rake 0.9.x warning (@mtylty, #1333)

Features:

  - Run the bundle install earlier in a Capistrano deployment (@cgriego, #1300)
  - Support hidden gemspec (@trans, @cldwalker, #827)
  - Make fetch_specs faster (@zeha, #1294)
  - Allow overriding development deps loaded by #gemspec (@lgierth, #1245)