.travis.yml: use long options

.travis.yml

@@ -11,7 +11,7 @@ before_install:
 before_script:
   
 script:
-  - git diff master.. -U0 README.md | grep -Pos "(?<=^\+).*" >> temp.md || (exit 0)
+  - git diff master.. --unified=0 README.md | grep --perl-regexp --only-matching --silent "(?<=^\+).*" >> temp.md || (exit 0)
   - node test.js temp.md
   - awesome_bot temp.md --allow-redirect || (exit 0)
   - awesome_bot README.md --allow-redirect || (exit 0)