Changes is bw2.proto and associated

SimilarDocumentInfo message removed from bw2.proto
1. replace with DocumentSimilarityInfo from document_similarity_out.proto
DocumentSimilarityInfo Java class regenerated from document_similarity_out.proto
1. before this pull request DocumentSimilarityInfo was not reflecting the current version of document_similarity_out.proto
2. double value replaced with float
Final fix to docsim serialization