Quote all string values to reduce probability of compose syntax errors (#51)

* Fix a bug where strings with special characters are not quoted

Before:
```
...
services:
  <service>:
    ....
    logging:
      options:
        tag: {{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}
        max-file: 3
    ...
```
and docker-compose up fails
after:
```
...
services:
  <service>:
    ....
    logging:
      options:
        tag: "{{.ImageName}}|{{.Name}}|{{.ImageFullID}}|{{.FullID}}"
        max-file: "3"
    ...
```
and docker-compose up works

* Remove no longer necessary workarounds

Author: Galaxy102

autocompose.py

@@ -117,29 +117,15 @@ def render(struct, args, networks, volumes):
     if args.version == 1:
         pyaml.p(OrderedDict(struct))
     else:
-        ans = {"version": '"3.6"', "services": struct}
+        ans = {"version": '3.6', "services": struct}
 
         if networks is not None:
             ans["networks"] = networks
 
         if volumes is not None:
             ans["volumes"] = volumes
 
-        pyaml.p(OrderedDict(ans))
-
-
-def is_date_or_time(s: str):
-    for parse_func in [datetime.date.fromisoformat, datetime.datetime.fromisoformat]:
-        try:
-            parse_func(s.rstrip("Z"))
-            return True
-        except ValueError:
-            pass
-    return False
-
-
-def fix_label(label: str):
-    return f"'{label}'" if is_date_or_time(label) else label
+        pyaml.p(OrderedDict(ans), string_val_style='"')
 
 
 def generate(cname, createvolumes=False):
@@ -171,7 +157,7 @@ def generate(cname, createvolumes=False):
         "environment": cattrs.get("Config", {}).get("Env", None),
         "extra_hosts": cattrs.get("HostConfig", {}).get("ExtraHosts", None),
         "image": cattrs.get("Config", {}).get("Image", None),
-        "labels": {label: fix_label(value) for label, value in cattrs.get("Config", {}).get("Labels", {}).items()},
+        "labels": cattrs.get("Config", {}).get("Labels", {}),
         "links": cattrs.get("HostConfig", {}).get("Links"),
         #'log_driver': cattrs.get('HostConfig']['LogConfig']['Type'],
         #'log_opt': cattrs.get('HostConfig']['LogConfig']['Config'],