Ensure bcrypt gets installed

Dockerfile

@@ -29,7 +29,9 @@ RUN cd /var/www && npm install
 RUN cd /var/www/sharelatex; \
 	npm install; \
 	grunt install; \
-	cd web/modules; \
+	cd web; \
+	npm install && npm install bcrypt; \
+	cd modules; \
 	git clone https://bitbucket.org/sharelatex/launchpad-webmodule.git launchpad; \
 	grunt compile;