language: ruby
rvm:
  - 1.9.3
  - 2.0.0
services:
  - mongodb

language: ruby
rvm:
  - 1.9.3
  - 2.0.0
services:
  - mongodb
before_install:
  - gem install bundler

Upgrade bundler to fix Travis CI error
Upgrade bundler to fix Travis CI error

Travis is throwing the following error

```ruby
NoMethodError: undefined method `spec' for nil:NilClass
```

Upgrading bundler seems to fix it as described in https://github.com/rubygems/rubygems/issues/1419