Features/lp/update config files docs

This PR is more for the sake of eliciting comment than anything else, in particular from @coderoshi, @macintux, @joedevivo. You can see a rendered Markdown version [here](https://github.com/basho/basho_docs/blob/features/lp/update-config-files-docs/source/languages/en/riak/ops/advanced/configs/configuration-files.md).

**pre-2.0**

I've transformed the original `app.config`/`vm.args` docs into a table-driven structure. I've retained the initial division of configs but have added sub-tables for some of the more complex ones, e.g. `default_bucket_properties`. I suspect, though, that it could use further subdivisions into smaller tables, because some of the tables, such as `riak_core`, are pretty unwieldy. Any input on preferred groupings would be great.

**2.0+**

Most of the actual written material here is drawn directly from the `riak.conf` from a typical `devrel` setup. I haven't massaged the language much, but I intend to (I also intend to append actual descriptions above each table). What I'm interested in at this point is how you guys feel about the groupings. Please let me know if you feel like the current division of configs is off somehow.