default create_with_value to a hash so we can eliminate conditionals, add test surrounding create_with(nil) behavior

* Only on postgresql, order("first asc, second asc") was invalid
* Closes #1720

  * Uses open source smoscript since scptxfr came out in 2000.
  * Uses sqlcmd which replaces osql.
  * Takes advantage of host/user/pass passed down by TinyTDS.

* amongst other things, allows meta_search to run against view-backed models

Fix inconsistencies by being polite to the wrapped body. Needed for Rack::Sendfile to function properly. See issue #1761.

Changed the default value for the options argument on ActiveRecord::ConnectionAdapters::Table#column_exists? from nil to an empty Hash {}.

That method calls through to ActiveRecord::ConnectionAdapters::SchemaStatements##column_exists? expects options to be a Hash.

When options was nil, an error would occur in cases where the column did exist because the called method attempted to perform a key lookup on options.

* Changes should better reflect present code behavior
* Related to issue: https://github.com/rails/rails/issues/1624

Perf fix - Use an instance variable instead of a class_attribute. Thanks @josevalim and @jhawthorn for the prompting.

Add support for using an ARCONFIG environment variable to specify the location of the config.yml file for running the tests

Make assert_no_queries literally enforce that there are no queries. As in, not a single line of SQL should be sent to the database, not even stuff that is ignored by assert_queries. The argument being that if you write assert_no_queries, you really do not want there to be any queries.

Don't wrap operations on collection associations in transactions when they are not needed, so the connection adapter does not send empty BEGIN COMMIT transactions blocks to the database.

* add/cleanup tests

Allow the connection pool's #table_exists? method to give the connections #table_exists? method a chance.