Allow to customize calico images names
Allow to customize calico images names

To have re-configurable CI and test calico code we need to have
an ability to add custom tags to calico images or push to
to different docker registers. By default:
   NODE_CONTAINER_NAME=calico/node:latest
   CTL_CONTAINER_NAME=calico/ctl:latest
   FELIX_CONTAINER_NAME=calico/felix:latest

Other changes:
 * replace path `calico_node` to `$NODE_CONTAINER_DIR`
 * get rid of `pwd` command, instead we define SOURCE_DIR as
   the place where calico-containers code is located

caseydavenport/calico-docker,insequent/calico-docker,projectcalico/calico-containers,Metaswitch/calico-docker,caseydavenport/calico-containers,projectcalico/calico-containers,caseydavenport/calico-containers,Metaswitch/calico-docker,insequent/calico-docker,caseydavenport/calico-docker,projectcalico/calico-docker,caseydavenport/calico-containers,projectcalico/calico-docker,projectcalico/calico-containers