Request for only metadata from archive.org.

Using http://archive.org/metadata/xxx/metadata to get only the metadta.
This won't include the information about all the files in the file,
saving some bandwidth.
Fixed an error in updating editions.

The code to making the request to solr was inside the for loop, making
to submit all the docs to solr once for each edition.
Include isbns and author info in edition docs when adding them to solr.
Fixed edition search for single core solr.