Merge pull request #372 from JewelJar/master

fixed broken Docker build.
diff --git a/Dockerfile b/Dockerfile
index 4d0a4ad..6728743 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -29,7 +29,7 @@
 
 # Build the local gddo files.
 ADD . /go/src/github.com/golang/gddo
-RUN go install github.com/golang/gddo/gddo-server
+RUN go get github.com/golang/gddo/gddo-server
 
 # Exposed ports and volumes.
 # /ssl should contain SSL certs.