This commit introduces a way by which we can now build multi-arch
 docker images for couchdb. Some of this work is inspired from the
 https://github.com/kubernetes/kubernetes/tree/master/build/debian-base

 This is the first cut and it can be enhanced based on the couchdb
 community's preference. This image is required atleast for the
 openwhisk project where we are driving the multi-arch support.

    Usage:

         `make build` ==> Retains the old behavior of builds
         `make build ARCH=ppc64le` ==> Builds it for a specific arch

Travis file is updated to use `make` instead of docker commandline to
do the builds.