Refactoring the config module to fle_utils

, to remove KA Lite-specific dependencies from securesync.

Goal is to get securesync down to 3 dependencies:
`annoying` (external dependency)
`chronograph`
`fle-utils`

Then, refactoring should be relatively easy...

All I did here was move `config` into `fle_utils` and update all imports.  I even added a docstring to `config`, @aronasorman  !