Log Message:
Update ruby-rspec-mocks to 3.4.0.

### 3.4.0 / 2015-11-11
[Full Changelog](http://github.com/rspec/rspec-mocks/compare/v3.3.2...v3.4.0)

Enhancements:

* Make `expect(...).to have_received` work without relying upon
  rspec-expectations. (Myron Marston, #978)
* Add option for failing tests when expectations are set on `nil`.
  (Liz Rush, #983)

Bug Fixes:

* Fix `have_received { ... }` so that any block passed when the message
  was received is forwarded to the `have_received` block. (Myron Marston, #1006)
* Fix infinite loop in error generator when stubbing `respond_to?`.
  (Alex Dowad, #1022)
* Fix issue with using `receive` on subclasses (at a class level) with 1.8.7.
  (Alex Dowad, #1026)