Fix syntax error in Dockerfile

Dockerfile

@@ -57,7 +57,7 @@ RUN cd /pip && \
         --find-links https://pyrepo.stage.mozaws.net/olympia/ \
         --no-index --no-deps \
         -r requirements/docker.txt && \
-    pip install -e /code &&
+    pip install -e /code && \
     rm -r build cache
 
 # Install the node_modules.