Allow to set app config with base64 input

[weyert]

If you want to set some long config value like some public key with lots of line breaks and spaces it's easier to this by the base64 encoding only currently this is not possible. Consider dokku_config in two modes plain and base64.

[ltalirz]

Are you aware of the pipe character in yaml? See e.g.

ansible-dokku/molecule/default/verify.yml

Lines 22 to 24 in 3797fc3

	msg: |
	hostname 'test.domain' not found in output of 'dokku domains':
	{{ dokku_domains.stdout }}

It allows you to simply copy-paste multiline strings - all you need to do is indent the block. See also https://yaml-multiline.info/

Using base64-encoded input makes it obviously no longer human-readable, so I am wondering whether this would be a good idea. I vote for closing this but let's hear what @josegonzalez has to say as well.

[josegonzalez]

I'm fine with adding base64 as an option, though certainly not as default. We can probably do the encoding in the library and have it be just a bool option on dokku_config.