Log Message:
Update ruby-arel package to 2.2.1.

== 2.2.1 / 2011-09-15

* Enhancements

  * Added UpdateManager#key to access the key value
  * Added SelectManager#projections= to override any existing projections
  * Added SelectManager#source to get the source of the last select core in the AST

== 2.2.0 / 2011-08-09

* Bug Fixes

  * The database connection caches visitors for generating SQL.
  * FALSE and TRUE nodes can be constructed.
  * Fixed ORDER BY / LIMIT clauses for UPDATE statements in Oracle.

== 2.1.4 / 2011-07-25

* Bug Fixes

  * Fix depth-first traversal to understand ascending / descending nodes.
  * Parentheis are suppressed with nested unions in MySQL. Thanks jhtwong!

== 2.1.3 / 2011-06-27

* Bug Fixues

  * Fixed broken gem build.

== 2.1.2 / 2011-06-27

* Bug Fixes

  * Visitors can define their own cache strategey so caches are not shared.
    Fixes #57
  * Informix support fixed.  Thanks Khronos.
  * Ordering nodes broken to subclasses.  Thanks Ernie Miller!
  * Reversal supported in ordering nodes.  Thanks Ernie Miller!

== 2.1.1 / 2011/05/14

* Bug fixes

  * Fixed thread safety bug in ToSql visitor.  Thanks Damon McCormick and
    Cameron Walters!

== 2.1.0 / 2011/04/30

* Enhancements

  * AST is now Enumerable
  * AND nodes are now n-ary nodes
  * SQL Literals may be used as Attribute names
  * Added Arel::Nodes::NamedFunction for representing generic SQL functions
  * Add Arel::SelectManager#limit=
  * Add Arel::SelectManager#offset
  * Add Arel::SelectManager#offset=
  * Added Arel::SelectManager#create_insert for building an insert manager.
  * SQL Literals are allowed for values in INSERT statements.
  * Math operations have been added to attributes, thanks to
    Vladimir Meremyanin.

* Bug fixes

  * MSSQL adds TOP to sub selects
  * Assigning nil to take() removes LIMIT from statement.
  * Assigning nil to offset() removes OFFSET from statement.
  * TableAlias leg ordering fixed

* Deprecations

  * Calls to `insert` are deprecated. Please use `compile_insert` then call
  `to_sql` on the resulting object and execute that SQL.

  * Calls to `update` are deprecated. Please use `compile_update` then call
  `to_sql` on the resulting object and execute that SQL.

  * Calls to `delete` are deprecated. Please use `compile_delete` then call
  `to_sql` on the resulting object and execute that SQL.

  * Arel::Table#joins is deprecated and will be removed in 3.0.0 with no
  replacement.

  * Arel::Table#columns is deprecated and will be removed in 3.0.0 with no
  replacement.

  * Arel::Table.table_cache is deprecated and will be removed in 3.0.0 with no
  replacement.

  * Arel::Nodes::And.new takes a single list instead of left and right.

  * Arel::Table#primary_key is deprecated and will be removed in 3.0.0 with no
  replacement.

  * Arel::SelectManager#where_clauses is deprecated and will be removed in
  3.0.0 with no replacement.

  * Arel::SelectManager#wheres is deprecated and will be removed in
  3.0.0 with no replacement.