Default location of configuration file

[tobijdc]

At the moment the only default location for the configuration file .nginx-linter.json is in the home directory (~/.nginx-linter.json).
This means if you use one configuration file per repository/project to have this consistent and use it in CI, you will always have to add --config .nginx-linter.json.

My proposal would be to:

• check for .nginx-linter.json in current directory
• if not found check ~/.nginx-linter.json

[jhinch]

Seems like a reasonable idea. You are welcome to raise a pull request if you wanted to contribute