Add flag to disable cache

[sk-]

As reported by @w4-sjcho: I'd like to use git lint from CI server, where the build agent has no permissions to modify files under home dir.

It would be great to have an option to disable cache completely.

[sk-]

@w4-sjcho out of curiosity, what CI server are you using?

[sjincho]

I'm using teamcity, where each agents run on docker containers under kubernetes.

We're currently working around the issue by making a separate launcher which overrides gitlint.utils.save_output_in_cache with a no-op function.

[quiin]

This would be a handy feature indeed.