remove some wordy lines of code and changed #move_to_root implementation
Stop testing on 1.8.7, 1.9.2, rbx-18mode, and rbx-19mode.
Adding Rails 4 and its dependent gems.

Unfortunately we can't just use only activerecord, since it's not released as stand alone gem.

Also:
* Replacing all .scoped calls with .all
* Using new order syntax on AR associations
* Replaced deprecated finder methods
* Using to_a for comparing activerecord relations in specs.
* Using correct activerecord syntax in nested_set_scope method
Use only activerecord, not all of Rails.
attr_accessible was removed from activerecord.
Let specs run and fix deprecation warnings about default_scope.
Prefer 2.0.0/1.9.3 to 1.8.x variants. Require database_cleaner.
Rewrite specs to check inclusion in array rather than absolute equality.
Fix test for JDBC
Merge pull request #176 from yuszuv/refactoring

remove some wordy lines of code and changed #move_to_root implementation
Delegate connection to class

Rails 4 has deprecated the instance connection method, this adds a delegation method back to skip the deprecation warning
move hardcode id to primary_key
Oracle does not support locks in subquery

Issue #166
using the quoted order column name
Merge pull request #188 from kangguru/master

Quote order_column_name
Merge pull request #186 from superimmo/master

Move hardcode id to primary_key
Merge pull request #187 from jhanggi/oracle_lock_166

Issue #166 Oracle does not support locks in subquery
Merge pull request #184 from lexrupy/rails4

Delegate connection to class
Fix ordering for left_sibling
Remove left_sibling order clause completely.

This is already handled by siblings via nested_set_scope