mime-types version

Impossible to use gem,  because use rails 3.2 and mime-types < 3.0 version
Bundler could not find compatible versions for gem "mime-types":
```
rails (= 3.2.22.5) was resolved to 3.2.22.5, which depends on
      actionmailer (= 3.2.22.5) was resolved to 3.2.22.5, which depends on
        mail (~> 2.5.4) was resolved to 2.5.5, which depends on
          mime-types (~> 1.16)
```