Don't ask how to install a linter when a non-conda interpreter is selected

[brettcannon]

The option to install using pip or conda is only relevant to conda which can support both. Otherwise you should just install using pip.

[brettcannon]

Also lowercase the names of the tools in the menu options.

[DonJayamanne]

I thought the extension already did this. Guess something must have changed and I have not added unit tests for this.

I stand corrected, it never did this.