Implemented the 'DefaultIfEmpty' operator. See #34
Implemented 'cast' operator
Added the MSDN link
Added a klass parameter
Implemented the 'ofType' operator
Used 'cast' to remove SuppressWarnings
Used 'isInstance' to replace 'isAssignableFrom' and added a unit test
Merge branch 'master' into cast
Merge branch 'master' into default_if_empty
do not run RxScalaDemo on each build,

because it does not do automatic testing
Implemented 'Synchronize' with 'lock'
add Documentation section to README
move examples from `src/main/scala` to `src/examples/scala`

and tweak build.gradle to make this work
move MovieLibUsage.java from project rxjava-scala-java to project rxjava-scala and delete project rxjava-scala-java
how to add RxJava core to scaladoc input
make Subscription an implicit value class
Merge pull request #409 from zsxwing/synchronize-lock

Implemented 'Synchronize' with 'lock'
Merge pull request #408 from samuelgruetter/idiomaticscala

Do not run RxScalaDemo on each build
Opening/Closing, Timestamped with unapply, BlockingObservable with WithFilter
Merge pull request #401 from zsxwing/default_if_empty

Implemented the 'DefaultIfEmpty' operator. See #34