cassandra_datum/base would attempt to encode all attributes
as strings using "#{value}" which incorrectly serializes hashes
to '{'key' => 'value'} when is then attempted to be parsed as json
when the attribute is read.

this commit fixes that by converting hashes and arrays using the to_json
method.
updated gem file
Merge pull request #15 from backupify/fix-hash-and-array-initialization

cassandra_datum/base would attempt to encode all attributes