Suppport prepared statements features

This pull request supports these features in rails.

- prepared statements can be disabled
https://github.com/rails/rails/commit/fd398475afb64e362059a500e5cd54d08b9afdee
- Created block to by-pass the prepared statement bindings.
https://github.com/rails/rails/commit/9f549212c3b6c8ae4684da61e03a04da9f341fad

Without this commit got these failures and errors. 
```ruby
3555 tests, 9445 assertions, 8 failures, 328 errors, 26 skips
```
One of the errors is
```ruby
$ ARCONN=oracle ruby -Itest test/cases/relations_test.rb -n test_relation_to_sql
Using oracle
Run options: -n test_relation_to_sql --seed 7721

# Running tests:

E

Finished tests in 0.653650s, 1.5299 tests/s, 0.0000 assertions/s.

  1) Error:
RelationTest#test_relation_to_sql:
NameError: uninitialized constant ActiveRecord::ConnectionAdapters::OracleAdapter::BindSubstitution
    /home/yahonda/git/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:122:in `unprepared_visitor'
    /home/yahonda/git/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:126:in `unprepared_statement'
    test/cases/relations_test.rb:718:in `test_relation_to_sql'

1 tests, 0 assertions, 0 failures, 1 errors, 0 skips
$
```