Update postgresql_adapter.rb

New ThinkingSphinx version 3.0> ignore option use_64_bit in thinking-sphinx.yml for PostgreSQL. sql_range_query: ERROR:  integer out of range (use_64_bit)
change #cast_to_timestamp, add test
Merge pull request #516 from arion/patch-1

Error in postgresql_adapter.rb (integer out of range - use_64_bit)