Add refile support

[omoshetech-t]

Add support for a modern file upload library. https://github.com/refile/refile

[mshibuya]

refile-mongoid should go into :mongoid group, since it is only required for mongoid builds.

[mshibuya]

CI build is failing, can you investigate?

[omoshetech-t]

refile-mongoid should go into :mongoid group, since it is only required for mongoid builds.

I'll fix it.

CI build is failing, can you investigate?

I forgot to check required Ruby version of the refile gem. It needs >= 2.1.0. This is one reason of build failure. So is it difficult to merge this request?

Build failures also occurred when satisfy refile required Ruby version. I can investigate reasons of this failures.

[mshibuya]

I forgot to check required Ruby version of the refile gem. It needs >= 2.1.0. This is one reason of build failure.

Then you can conditionally install(and test) refile gem for Ruby >= 2.1.0. To merge in, passing all builds is mandatory.

[omoshetech-t]

I add conditional statements of Ruby version for build failures fix.

The build failures when satisfy refile required Ruby version, cause sass-rails version.
sass-rails 5.0.0 is installed when I add gem "refile", ">= 0.5.5" to rails_4.2.gemfile, but this project needs sass-rails >= 5.0.2. If I don't add gem "refile", ">= 0.5.5", sass-rails 5.0.3 is installed. This problem doesn't occur bundler version >= 1.9.0.pre. rails_4.0.gemfile and rails_4.1.gemfile also have sass-rails version problem but they are a little different. In this case, sass-rails 4.0.0 is installed.

I cannot investigate detailed reason. However I found a workaround. If I add gem "sass-rails", "~> 5.0" and gem "refile", "~> 0.5" to Gemfile, bundler installs the correct version of sass-rails.

Then all tests have been passed now.

[mshibuya]

Merged in, thanks 🙆‍♀️