testing: see if docker is present on travis if we don't specify language

Signed-off-by: Paul Osborne <[email protected]>

Author: posborne

.travis.yml

@@ -2,7 +2,9 @@
 sudo: required
 services:
   - docker
-language: rust
+
+# language: rust
+
 # rust:
 #   - 1.1.0  # Oldest supported version
 #   - 1.2.0