Support alternate Dockerfile name.

Signed-off-by: Kyle James Walker <KyleJamesWalker@gmail.com>

compose/cli/docker_client.py

@@ -32,4 +32,4 @@ def docker_client():
         )
 
     timeout = int(os.environ.get('DOCKER_CLIENT_TIMEOUT', 60))
-    return Client(base_url=base_url, tls=tls_config, version='1.15', timeout=timeout)
+    return Client(base_url=base_url, tls=tls_config, version='1.17', timeout=timeout)

compose/config.py

@@ -33,6 +33,7 @@ DOCKER_CONFIG_KEYS = [
 
 ALLOWED_KEYS = DOCKER_CONFIG_KEYS + [
     'build',
+    'dockerfile',
     'expose',
     'external_links',
     'name',

compose/service.py

@@ -474,6 +474,7 @@ class Service(object):
             stream=True,
             rm=True,
             nocache=no_cache,
+            dockerfile=self.options.get('dockerfile', None),
         )
 
         try: