Adding upstream version 1.2.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

.travis.yml

@@ -0,0 +1,23 @@
+language: go
+os:
+  - linux
+  - osx
+env:
+  - GO111MODULE=on
+install:
+  - go version
+  - go env
+  - go get -t -d -v ./...
+script:
+  - go build ./selfupdate/
+  - go build ./cmd/selfupdate-example/
+  - go build ./cmd/detect-latest-release/
+  - go build ./cmd/go-get-release/
+  - |
+    if [[ "${GITHUB_TOKEN}" != "" ]]; then
+      go test -v -race -coverprofile=coverage.txt ./selfupdate
+    else
+      go test -v -race -short ./selfupdate
+    fi
+after_success:
+  - if [ -f coverage.txt ]; then bash <(curl -s https://codecov.io/bash); fi