Have a config command

[adoble]

If some of the previous issues are implemented we are starting to have a number of options. Having all these handled during init is maybe too much and a developer may want to change them after initialization.

Propose a config command, e.g.:

adr config editor /usr/bin/vim
adr config dir docs/records
adr config template ~/templates/madr
adr config format asciidoc

[adoble]

Subcommand config added:

Usage: adr config [COMMAND]
List of the currently set properties.
Subcommands:
author Change the default name of the ADR author.
dateFormat Change how the dates in the ADRs are represented.
docPath Change the location where future ADRs are stored.
templateFile Change the template file used to created ADRs.