Merge branch 'kvo-dealloc-race' into fix-kvo-capturing-self

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa/NSObject+RACPropertySubscribing.m
	ReactiveCocoaFramework/ReactiveCocoa/RACSignal+Operations.m
Remove `observer` parameter from all KVO APIs

Fixes #472.
Merge branch '3.0-development' into fix-kvo-capturing-self

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa/NSObject+RACPropertySubscribing.m
Merge branch '3.0-development' into fix-kvo-capturing-self
Warn about new RACObserve behavior

Only when WE_PROMISE_TO_MIGRATE_TO_REACTIVECOCOA_3_0 is defined,
and when observing something other than `self`.
Clarify warning behavior, use plain token pasting
Restore deprecated RACKVOWrapper method
Restore deprecated RACPropertySubscribing method
Merge branch '3.0-development' into fix-kvo-capturing-self
Stub new CHANGELOG section
CHANGELOG
Change updated examples into "to update" section
Allow deprecation warnings in unit tests
Move RACReplaySubject tests into their own file

We’re going to keep them around because the class will continue to
exist, so we want to only suppress deprecation messages there.

Really, this is how it should’ve been organized in the first place.
Remove RACCommandSpec
Remove RACSequence specs
Test fixes for various deprecated methods
Remove tests for -tupleByAddingObject:
Remove RACMulticastConnectionSpec
Remove tests for -scheduleRecursiveBlock: