Add dockerversion to factory-parameters

Currently, imagefactory's docker plugin will default an older
version of the metadata imager format that is not compatible with
the latest versions of docker. This change tells the plugin to use
the docker version "1.10.1" metadata format which is compatible with
all currently available docker releases.

Signed-off-by: Adam Miller <maxamillion@fedoraproject.org>

fedora-docker.conf

@@ -223,6 +223,7 @@ image_build = {
                     'subvariant': 'Docker_Base'
                     },
             'factory-parameters': {
+                'dockerversion': "1.10.1",
                 'docker_cmd':  "[ '/bin/bash' ]",
                 'docker_env': "[ 'DISTTAG=f25docker', 'FGC=f25' ]",
                 'docker_labels': {

fedora.conf

@@ -290,6 +290,7 @@ image_build = {
                     'failable': ['*'],
                     },
             'factory-parameters': {
+                'dockerversion': "1.10.1",
                 'docker_cmd':  "[ '/bin/bash' ]",
                 'docker_env': "[ 'DISTTAG=f25docker', 'FGC=f25' ]",
                 'docker_labels': {