There is a bug in trusted proxies: https://github.com/rails/rails/issues/5223
This commit adds a monkey patch to fix the bug.

Example of errors:

```
1) trusted_proxies with default config preserves private IPs
    Failure/Error: expect(request.ip).to eq('10.1.5.89')

      expected: "10.1.5.89"
          got: nil

      (compared using ==)
    # ./spec/initializers/trusted_proxies_spec.rb:12:in `block (3 levels) in <top (required)>'

2) trusted_proxies with default config filters out localhost
    Failure/Error: expect(request.ip).to eq('10.1.5.89')

      expected: "10.1.5.89"
          got: "1.1.1.1"

      (compared using ==)
    # ./spec/initializers/trusted_proxies_spec.rb:18:in `block (3 levels) in <top (required)>'
```