Observable.sample(Observable) in Scala
tweak RxScalaDemo (and Olympics example)
some RxScalaDemo tweaks
add Subscriber and Observable creation from `Subscriber[T] => Unit`
Merge branch 'master' of github.com:Netflix/RxJava into scala-additions
deprecate rx.lang.scala.Observable.create[T](Observer[T]=>Subscription)
correct link to maven search
A number of improvements to OperatorObserveFromAndroidComponent

- move the UI thread assert out of the operator and into the helpers; this way, we don't fail the observer anymore with an exception, but the caller.
- do not loop unsubscribe through the main thread anymore. This unnecessarily defers releasing the references, and might in fact be processed only after Android creates the component after a rotation change. I had to make the references volatile for this to work.
- immediately unsubscribe in case we detect the componentRef has become invalid. This solves the problem that dangling observers would continue to listen to notifications with no observer alive anymore.

refs:
https://github.com/Netflix/RxJava/issues/754
https://github.com/Netflix/RxJava/issues/899
Implemented Skip using Lift in Observable and OperatorSkip
Deleted non-time part from OperationSkip
Moved tests to OperatorSkipTest
add Observable.startWith(Observable) method and unit test to avoid breaking method chaining when want to startWith an Observable rather than just an Iterator or specific values.
add space to a comment to force ci rebuild to see if suspected non-deterministic test fails again
Fixed state capture bug.
Added some additional tests
refactor the debug hooks before they become a breaking change.
Merge pull request #936 from Applied-Duality/SkipFixed

Skip fixed
math-module

Moving the average/sum/min/max functionality to the MathObservable similar to StringObservable.
Merge pull request #942 from benjchristensen/math-module

MathObservable
OperationRetry -> OperatorRetry

Updated to use "lift" and Subscriber.
Fixes https://github.com/Netflix/RxJava/issues/943 Observable.retry() does not unsubscribe from source
Merge pull request #944 from benjchristensen/operator-retry

OperationRetry -> OperatorRetry
Merge branch 'clean-up-hook-args' of github.com:abersnaze/RxJava into merge-940

Conflicts:
	rxjava-core/src/main/java/rx/Observable.java
Merge pull request #945 from benjchristensen/merge-940

Manual Merge 940