Rename yaml_load() to direct_yaml_load() and rename cached_yaml_load() to yaml_load()

As discussed in #92, rename `yaml_load()` to `direct_yaml_load()` and rename `cached_yaml_load()` to `yaml_load()`.

Looks like `committee_meetings.py` was the only remaining `yaml_load()` dependency in the congress codebase, so I changed that. (Pseudo-apologies for the trailing whitespace removal.)

So now the only place where `direct_yaml_load()` is used in place of the caching `yaml_load()` is not used is in `yaml_load()` itself, and the config file loading at the top of the utils file, as that never used `yaml_load()` in the first place, and I thought it best not to cache that file.

From now on, it's safe to use `yaml_load()` as long as you are cache-agnostic. (Just pass in the regular filename/path; `yaml_load()` will worry about the caching.)