Move JoinDependency and friends from ActiveRecord::Associations::ClassMethods to just ActiveRecord::Associations

Previous version (after commit 3103296a) was generating wrong SQL for Oracle when calling exists? method on HABTM association.

ActiveRecord::Relation#primary_key should return a string, just like ActiveRecord::Base.primary_key does.

Fixes queries using limits and punctuation in order, removes order("col1, col2") usage in favor of order(["col1", "col2"})

[#4597 state:committed]

Refactoring JoinDependency and friends. This improves the code (IMO) including adding some explanatory comments, but more importantly structures it in such a way as to allow a JoinAssociation to produce an arbitrary number of actual joins, which will be necessary for nested has many through support. Also added 3 tests covering functionality which existed but was not previously covered.

This will hopefully make Active Record run a bit more faster.

This will hopefully make Active Record run a bit more faster.

Fix the #using_limitable_reflections? helper to work correctly by not examining the length of an array which contains false/true, hence always passing. [#4869 state:resolved]
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Make find_or_create and find_or_initialize work mixing explicit parameters and a hash [#4457 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

[#4463 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>