Enforce file, directory, and variable name case / characters

[jeffmcutter]

I think it would be useful for ansible-lint to enforce standards regarding the case and characters used for naming files, directories, and variables.

For example, If I remember correctly...

• Variables should be lowercase alpha/numeric with alpha first and with underscores
• Directory names / role names should be lower case with underscores
• File names (task files, playbooks, etc.) should be lower case with dashes (or maybe underscores too).

I'm not sure maybe if ansible-lint is doing some of this already, but recently encountered some UPPER_CASE_FILES.yml and UPPER_CASE_VARIABLES that passed lint.