Use compose-go + improvements (#9)

Use compose-go https://github.com/compose-spec/compose-go  to make Katenary parsing compose file the official way.
Add labels:
- `volume-from` (with `same-pod`) to avoid volume repetition
- `ignore` to ignore a service
- `mapenv` (replaces the `env-to-service`) to map environment to helm variable (as a template string)
- `secret-vars` declares variables as secret values

More:
- Now, environment (as secret vars) are set in values.yaml
- Ingress has got annotations in values.yaml
- Probes (liveness probe) are improved
- fixed code to optimize
- many others fixes about path, bad volume check, refactorisation, tests...

examples/ghost/docker-compose.yaml

@@ -0,0 +1,30 @@
+version: "3"
+
+services:
+  blog:
+    image: ghost
+    environment:
+      # this is OK for local test, but not with Helm
+      # because the URL depends on Ingress
+      url: http://ghost.example.localhost
+    labels:
+      katenary.io/ports: 2368
+      katenary.io/ingress: 2368
+      # ... so we declare that "url" is actually
+      # the ingress host
+      katenary.io/mapenv: |
+        url: http://{{ .Values.blog.ingress.host }}
+
+  proxy:
+    # A simple proxy for localhost
+    image: quay.io/pathwae/proxy
+    environment:
+      CONFIG: |
+        ghost.example.localhost:
+          to: http://blog:2368
+    ports:
+      - 80:80
+    labels:
+      # we don't want this in Helm because we will use
+      # an ingress
+      katenary.io/ignore: true