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

close #1054
Merge pull request #1057 from zsxwing/issue-1044

Fix issue #1044
Merge pull request #1056 from zsxwing/scala-drop

Add drop(skip) and dropRight(skipLast) to rxscala