MAINT fix ci script

Author: mfeurer

ci_scripts/install.sh

@@ -28,7 +28,7 @@ conda create -n testenv --yes python=$PYTHON_VERSION pip nose
 source activate testenv
 
 # Install requirements in correct order
-pip install -r requirements.txt
+cat requirements.txt | xargs -n 1 -L 1 pip install
 
 if [[ "$COVERAGE" == "true" ]]; then
     pip install coverage coveralls

doc/index.rst

@@ -56,7 +56,7 @@ Please install all dependencies manually with:
 
 .. code:: bash
 
-    pip install -r https://raw.githubusercontent.com/automl/auto-sklearn/master/requirements.txt
+    cat https://raw.githubusercontent.com/automl/auto-sklearn/master/requirements.txt | xargs -n 1 -L 1 pip install
 
 Then install *auto-sklearn*