Use data/solr_dumps/dumps/ instead of data/solr_dumps/
Use data/solr_dumps/dumps/ instead of data/solr_dumps/

* Easier to `rm -rf` without removing .gitignore too
* Possible to symlink data/solr_dumps/dumps/ without making repository unclean

Something like data/solr_import/dumps/ would probably make more sense, but there’s a risk that one of us will accidentally `rm -rf data/solr/` instead.

berkmancenter/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud