bundler/bundler — pull request #3314 by aderyabin (2014-12-17 15:47:06+00:00)
Title: add operators to Ruby version comparison

Currently I can point Ruby version toughly:
```ruby
ruby '2.1.0'
```

But sometimes we need to set flexible version. For example that Ruby is not so old:
```ruby
ruby '>= 2.0.0'
```