Revert "NullObject inherits from BasicObject"

This reverts commit 88bdab8a7737e2fe2af1dc862dd73785537f7220.
Revert "Remove support for Ruby 1.8"

This reverts commit 0ed8d32c7c237be3ab5d7874c4be1df1f925d387.
More on streaming
Prepare for version 5.0.0.rc.1 release