Clean Data!

This pull request modifies the S&H import script to import "clean" data into the database. Run like this:

```
bundle exec rails r ./lib/import_science_health.rb
```

There's currently some discussion going on regarding if we want split the data by paragraph or by sentence. the `import_science_health.rb` script will import by sentences by default, but you can tell it to import by paragraph by passing the `-p` option:

```
bundle exec rails r ./lib/import_science_health.rb -p
```