replace Observable.apply(rx.Observable) by toScalaObservable

and move Java types <=> Scala types conversions from
ImplicitFunctionConversions to JavaConversions
rename Observable constructors
add equals, hashCode, toString to Notifications
add Observable.from(Future) constructor
Operator GroupJoin v2
Manually merge branch 'master' of github.com:Netflix/RxJava into scala-constructors

Conflicts:
	language-adaptors/rxjava-scala/src/examples/scala/rx/lang/scala/examples/RxScalaDemo.scala
	language-adaptors/rxjava-scala/src/main/scala/rx/lang/scala/ImplicitFunctionConversions.scala
	language-adaptors/rxjava-scala/src/main/scala/rx/lang/scala/Observable.scala
Operation Timestamp with Scheduler
Merge pull request #561 from samuelgruetter/scala-constructors

Creating Observables in Scala: Approach04
Merge pull request #565 from akarnokd/GroupJoin2

Operator GroupJoin v2
Merge pull request #567 from akarnokd/TimestampWithScheduler

Operation Timestamp with Scheduler
javadoc improvements (groupJoin, groupByUntil, timestamp w/scheduler)
Merge pull request #569 from Netflix/docs

javadoc improvements (groupJoin, groupByUntil, timestamp w/scheduler)
Fixed the blocking/non-blocking first
Add MSDN links
Mark takeFirst deprecated