JVMCBC-78: Upgrade RxJava to 1.0.2 GA

Motivation
----------
1.0.2 contains an important enhancement which makes sure that
scheduled actions are not interrupting themselves, which reduces
the bookkeeping that the JVM needs to do, leading to better performance
and less GC cycles.

Fore more information, see https://github.com/ReactiveX/RxJava/issues/1913

Modifications
-------------
Updating the dependency.

Result
------
Less bookeeping in the JVM, leading to a more smooth steady state.

Change-Id: I9b62169f66f7490c047867533e321e668d7db9eb
Reviewed-on: http://review.couchbase.org/43824
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>