config.js: small updates

* moved json & yaml file type setting into config.arrange_args with the
.ini setting.
* added binary type to type list in docs/Config.md
* adds yaml to the list of recognized fs_types
* line shortening (lint)
* replaced cascading if else’s with switch/case (2x)
* renamed configloader -> cfreader (consistent with use elsewhere)

The changes to a config.arrangeargs are well covered by the tests I wrote long ago and the changes in configfile.js are mostly covered by the tests added in #793. What I'm uncertain of is how this might affect the caching / watching of YAML files.