Merge branch 'build_prune' of https://github.com/The-Loeki/docker-py into The-Loeki-build_prune

Signed-off-by: Joffrey F <joffrey@docker.com>

docker/api/build.py

@@ -305,6 +305,22 @@ class BuildApiMixin(object):
         else:
             log.debug('No auth config found')
 
+    @utils.minimum_version('1.31')
+    def prune_build(self):
+        """
+        Delete builder cache
+
+        Returns:
+            (dict): A dict containing
+            the amount of disk space reclaimed in bytes.
+
+        Raises:
+            :py:class:`docker.errors.APIError`
+                If the server returns an error.
+        """
+        url = self._url("/build/prune")
+        return self._result(self._post(url), True)
+
 
 def process_dockerfile(dockerfile, path):
     if not dockerfile: