Add pgp-Filetypes as a default

[kakohari]

ASCII-armored PGP-keys should be uploaded to a sites imprint to communicate encrypted via mail.
added .asc into plugins GUI but still not allowed to upload (or is this a WP6-related issue?).

edit: some itchy keyboard, the title should not have / make at the end. Sorry!

[kkarpieszuk]

@kakohari we are going to fix this in already reported ticket #53

If you want to be informed about the progress, please open #53 page and click "Watch" at the top of the screen.

Additionally, please see that at the bottom of the opening post of #53 there is possible way how to guess the correct mime type which must be set for the file you want to upload.