Fix goreleaser for multi-platform dockers

[mhemeryck]

Proposed patch:

commit a737447e1bdd9dbe7402ea3ae47d78b4529fa70b
Author: Martijn Hemeryck <martijn.hemeryck@gmail.com>
Date:   Fri Sep 21 13:33:48 2018 +0200

    Multi-arch dockers

diff --git a/.goreleaser.yml b/.goreleaser.yml
index fbcf1a5..e66d1b1 100644
--- a/.goreleaser.yml
+++ b/.goreleaser.yml
@@ -1,14 +1,14 @@
 builds:
 -
   env:
-    - CGO_ENABLED=0
+  - CGO_ENABLED=0
   goos:
-    - linux
+  - linux
   goarch:
-    - amd64
-    - arm
+  - amd64
+  - arm
   goarm:
-    - 7
+  - 7
 archive:
   replacements:
     linux: Linux
@@ -16,9 +16,28 @@ archive:
 checksum:
   name_template: 'checksums.txt'
 snapshot:
-  name_template: "{{ .Tag }}-next"
+  name_template: "{{ .Commit }}"
 dockers:
   -
     image: mhemeryck/modbridge
+    goarch: amd64
+    goos: linux
+    tag_templates:
+    - "{{ .Tag }}"
+    - "{{ .Arch }}-{{ .Tag }}"
+    - "{{ .Arch }}-latest"
+    - "{{ .Arch }}"
+    - latest
+    extra_files:
+    - config.yml
+  -
+    image: mhemeryck/modbridge
+    goarch: arm
+    goarm: 7
+    goos: linux
+    tag_templates:
+    - "{{ .Arch }}v{{ .Arm }}-{{ .Tag }}"
+    - "{{ .Arch }}v{{ .Arm }}-latest"
+    - "{{ .Arch }}v{{ .Arm }}"
     extra_files:
     - config.yml

Multi-arch part is not working atm, so leaving it here.