Fixed select_rows() to actual support binds via do_exec_query()

Without this fix, the following test is failing with rails 4.0.4:

```
  1) Error:
ActiveRecord::AdapterTest#test_select_methods_passing_a_association_relation:
ActiveRecord::StatementInvalid: TinyTds::Error: Must declare the scalar variable "@0".: SELECT title FROM [posts] WHERE [posts].[author_id] = @0
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:421:in `each'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:421:in `handle_to_names_and_values_dblib'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:410:in `handle_to_names_and_values'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:383:in `_raw_select'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:378:in `block in raw_select'
    /Users/wbond/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/bundler/gems/rails-2abe4b032d08/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:442:in `block in log'
    /Users/wbond/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/bundler/gems/rails-2abe4b032d08/activesupport/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    /Users/wbond/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/bundler/gems/rails-2abe4b032d08/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:437:in `log'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:378:in `raw_select'
    /Users/wbond/dev/veracross/activerecord-sqlserver-adapter/lib/active_record/connection_adapters/sqlserver/database_statements.rb:7:in `select_rows'
    /Users/wbond/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/bundler/gems/rails-2abe4b032d08/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:56:in `select_values'
    /Users/wbond/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/bundler/gems/rails-2abe4b032d08/activerecord/test/cases/adapter_test.rb:192:in `test_select_methods_passing_a_association_relation'
```

It seems one of the tests now uses a bind with select_rows(), which wasn't actually implemented before.