change install & script in travis yml

Author: cake17

.travis.yml

@@ -4,10 +4,9 @@ python:
  - "2.7"
 
 install:
-    - pip install sphinx==1.2.3
-    - pip install sphinxcontrib-phpdomain
+    - pip install -r requirements.txt
 
-script: "make html"
+script: 'make html SPHINXOPTS="-W"'
 
 sudo: false