Add TravisCI Ruby 2.5.1 builds
Add TravisCI Ruby 2.5.1 builds

biow0lf/shoulda-matchers,reacuna/shoulda-matchers,guialbuk/shoulda-matchers,guialbuk/shoulda-matchers,guialbuk/shoulda-matchers,reacuna/shoulda-matchers,thoughtbot/shoulda-matchers,thoughtbot/shoulda-matchers,biow0lf/shoulda-matchers,biow0lf/shoulda-matchers,reacuna/shoulda-matchers,biow0lf/shoulda-matchers,guialbuk/shoulda-matchers,thoughtbot/shoulda-matchers,thoughtbot/shoulda-matchers,reacuna/shoulda-matchers