Notifications: extract central Notifier, cordon off the internal Fanout implementation, and segregate instrumentation concerns

Revert "Create SyncListener. Since they do not rely on Thread, they can be used on Google App Engine."

Take a step back on this API direction.

This reverts commit 8104f65c.

Signed-off-by: NMichael Koziarski <michael@koziarski.com>

Conflicts:

	actionmailer/lib/action_mailer/base.rb

Obviated by fix in macruby trunk.

This reverts commit 6d91e7dc.

controller test loading.

Update rails application root detection to take into consideration a callstack that includes the rack library

changed.

Revert "Revert "Assert primary key does not exist in habtm when the association is defined, instead of doing that everytime a record is inserted.""

This reverts commit 2b82708b.

[#3128 state:resolved]

Conflicts:

	activerecord/lib/active_record/associations.rb
	activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb

Signed-off-by: NYehuda Katz <wycats@Yehuda-Katz.local>

Signed-off-by: NYehuda Katz <wycats@Yehuda-Katz.local>

Signed-off-by: NYehuda Katz <wycats@Yehuda-Katz.local>