Supports `has_attribute?` for `mock_model` doubles

Fixes #956

Fixes #924 for 2.14

fixes #922

Per <https://github.com/rails/rails/pull/13605#issuecomment-31626172>,
always load the base "active_support" file before loading specific parts
of active_support.

As far as I can tell, these versions will never have new releases.

Failure message for should_not route_to properly includes expected options

[ci skip]

[ci skip]

2.14: Blow away the view cache between specs

Merge #871 into 2-14

Rubinius test unit patch

One of our cukes was failing because Rails caches templates and the
differing format seems not to be enough to invalidate it automatically,
I'm going to open a Rails patch for this but in the mean time this fixes
that cuke.