combine image build steps

Dockerfile

@@ -1,3 +1,16 @@
+FROM quay.io/vektorcloud/go:1.8
+
+RUN apk add --no-cache make
+
+COPY glide.* /go/src/github.com/bcicen/ctop/
+WORKDIR /go/src/github.com/bcicen/ctop/
+RUN glide install
+
+COPY . /go/src/github.com/bcicen/ctop
+RUN make build && \
+    mkdir -p /go/bin && \
+    mv -v ctop /go/bin/
+
 FROM scratch
-COPY ./ctop /ctop
+COPY --from=0 /go/bin/ctop /ctop
 ENTRYPOINT ["/ctop"]