Cd first, then install

Author: Emmanouil Konstantinidis

.travis.yml

@@ -12,7 +12,7 @@ env:
   - DJANGO_VERSION=1.9
 
 install:
-  - npm install
+  - cd rest_framework_docs/static/ && npm install
   - pip install -r requirements.txt
   - pip install -U Django==$DJANGO_VERSION
   - pip install codecov