Fix Travis config not to run on every branch but just master
Fix Travis config not to run on every branch but just master

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