Move rx.joins to rxjava-joins module

Migrating rx.joins into a separate contrib module as part of roadmap to 1.0: https://github.com/Netflix/RxJava/issues/1001#issuecomment-40390984
This is being done until the rx.joins API has further time to mature as it is likely to change and we can't make breaking changes any further once we hit 1.0.
Merge pull request #1049 from benjchristensen/joins-module

Move rx.joins to rxjava-joins module
Reimplement "SkipLast" operator
Rename OperationSkipLast to OperatorSkipLast
Reimplement the "SkipLast" operator with time
Replace LinkedList with ArrayDeque
Merge branch 'single' of git://github.com/zsxwing/RxJava into merge-967

Conflicts:
	rxjava-core/src/main/java/rx/Observable.java
	rxjava-core/src/main/java/rx/operators/OperationSingle.java
	rxjava-core/src/test/java/rx/operators/OperatorLastTest.java
Merge pull request #1051 from benjchristensen/merge-967

Manual Merge #967
Merge pull request #1050 from zsxwing/skip-last

Reimplement the 'SkipLast' operator
ComputationScheduler -> EventLoopsScheduler

- This implementation is used by Schedulers.computation() but is actually a pool of event loops, so renaming.
Restoring parallel() to using Schedulers.computation()

See https://github.com/Netflix/RxJava/issues/713 for background on this.
Merge pull request #1052 from benjchristensen/computation-scheduler

Scheduler Cleanup
Remove deprecated rx.util.functions.*

- organized imports and fixed few places that were still accidentally using the old package
Remove deprecated methods/classes from rxjava-core

Cleanup on path to 1.0: https://github.com/Netflix/RxJava/issues/1001#issuecomment-40888251
Merge pull request #1053 from benjchristensen/deprecation-cleanup

Deprecation Cleanup
close #1054
Add drop and dropRight to rxscala
Fix issue #1044
Deprecate Observable.apply
Merge pull request #1055 from puniverse/master

close #1054