Support for Intents

[sghosh151]

Having a set of labels be available to support intents as described in moby/moby#11187.

Do we have to worry about datatypes for labels? - string vs json blob?

[rhatdan]

@sghosh151 During the LABEL discussion at docker, they really wanted to avoid JSON data in the labels, and wanted to stick to strings. Feeling that JSON data in locations like Dockerfiles would quickly become difficult to use for non expert users.

[cgwalters]

Strings only forces e.g. the RUN label down the path of shell script for command execution. It's convenient but as soon as you have arguments that need to be quoted you're into shell quoting hell. Docker learned that lesson and changed RUN to support an array syntax too.