Make sure /.config and /.npm directory are writable for all users.

This is mainly for the builds, within a docker container, on Apache jenkins to work properly.
diff --git a/Dockerfile b/Dockerfile
index 010cba5..15cf2bf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,6 +21,8 @@
 # Install necessary binaries to build brooklyn-ui
 RUN apt-get update && apt-get install -y git-core \
     libpng-dev \
+    libjpeg-progs \
+    pngquant \
     make \
     automake \
     autoconf \
@@ -30,5 +32,10 @@
     nasm \
     gcc
 
+# Make sure the /.config && /.npm (for UI module builds) is writable for all users
+RUN mkdir -p /.config && chmod -R 777 /.config
+RUN mkdir -p /.npm && chmod -R 777 /.npm
+
+# Make sure the /var/maven is writable for all users
 RUN mkdir -p /var/maven/.m2/ && chmod -R 777 /var/maven/
 ENV MAVEN_CONFIG=/var/maven/.m2