[build] fix pip install issues on OSX High Sierra (#6201)

* [build] fix pip install issues on OSX High Sierra

I think requirements.txt was out-of-sync as well.

Also had to:
export
  LDFLAGS="-L/usr/local/opt/openssl/lib"
export
  CPPFLAGS="-I/usr/local/opt/openssl/include"
export
  PKG_CONFIG_PATH="/usr/local/opt/openssl/lib/pkgconfig"

* Fix click

contrib/docker/Dockerfile

@@ -36,7 +36,9 @@ WORKDIR $HOME/incubator-superset
 COPY ./ ./
 
 RUN pip install --upgrade setuptools pip
-RUN pip install -e . && pip install -r requirements-dev.txt
+RUN pip install -r requirements.txt
+RUN pip install -r requirements-dev.txt
+RUN pip install -e .
 
 ENV PATH=/home/work/incubator-superset/superset/bin:$PATH \
     PYTHONPATH=./superset/:$PYTHONPATH

contrib/docker/docker-init.sh

@@ -9,7 +9,7 @@ fabmanager create-admin --app superset
 superset db upgrade
 
 # Load some data to play with
-superset load-examples
+superset load_examples
 
 # Create default roles and permissions
 superset init