Fix path for 
Fix path for 

This fixes the follwing error:
```
/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- response/elvanto_exception_middleware (LoadError)
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /var/lib/gems/2.3.0/gems/elvanto-api-1.0.1/lib/elvanto/client.rb:5:in `<top (required)>'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /var/lib/gems/2.3.0/gems/elvanto-api-1.0.1/lib/elvanto.rb:6:in `<top (required)>'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:127:in `require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:127:in `rescue in require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:40:in `require'
        from create.rb:2:in `<main>'
```
elvanto/api-ruby