Refactor and add new build routines

- Fix version injection in build
- Refactor Makefile
- Add --new-config flag to generate sample config
- Add license
- Remove autogenerated frontend README
- Refactor make dist to do end-to-end build
- Refactor build and add goreleaser conf

.goreleaser.yml

@@ -0,0 +1,29 @@
+env:
+  - GO111MODULE=on
+  - RELEASE_BUILDS=dist/listmonk_darwin_amd64/listmonk dist/listmonk_linux_amd64/listmonk dist/listmonk_windows_amd64//listmonk.exe
+
+before:
+  hooks:
+    - make build-frontend
+
+builds:
+  - binary: listmonk
+    goos:
+      - windows
+      - darwin
+      - linux
+    goarch:
+      - amd64
+    ldflags:
+      - -s -w -X "main.buildString={{ .Tag }} ({{ .ShortCommit }} {{ .Date }})"
+
+    hooks:
+      # stuff executables with static assets.
+      post: make pack-releases
+
+archives:
+  - format: tar.gz
+    files:
+      - config.toml.sample
+      - README.md
+      - LICENSE