clean up buildout configs

now you can use:

  - `buildout.cfg` to set up solr 3.6.x
  - `solr-4.3.x.cfg` to set up solr 4.3.x
  - `solr-4.4.x.cfg` to set up solr 4.4.x
  - `travis.cfg` to run on travis against solr 4.4.x