Output deprecation warning when at_least(0) is sent

See https://github.com/rspec/rspec-mocks/issues/133
only one expectation for deprecation warning
better expectation messages
also test for correct deprecation warning
output deprecation warning on #any_number_of_times
Move `HaveReceived` matcher into `Matchers` module namespace.
Add new expect/allow syntax.
Add syntax configuration options.
Fix `any_instance` so it doesn't rely upon `should_receive`/`stub` being on every object.
Don't rely upon #null_object? being on every object.

This is based upon the logic in https://github.com/rspec/rspec-expectations/commit/5fbe94ae574b0daa10869675dfe0a675d268ec0b .

This is the last change we need to be able to use the :wrapped syntax with the :direct syntax disabled.
Normalize methods to symbols to get spec to pass on 1.8.7.
Remove obselete cucumber scenario.

With the changes for the new syntax, and the available config options,
`stub`, `should_receive` and `should_not_receive` are added to every
object initially (before RSpec::Mocks.setup) is called, but the config
can be set to remove them.
Fully qualify all constants.

On 1.9.2 I was getting failures like:

uninitialized constant BasicObject::Hash
Ensure the backtrace line is reported consistently.

MRI is different from JRuby and RBX in this regard. This should
get the travis build to pass, I hope.
Allow the new syntax to be used w/o rspec-expectations.

Here we conditionally define `expect` in a superclass module
so that it is available, but `RSpec::Matchers` can still be
included later to override it.

Note: with this in place, `expect` won't be undefined when the
new syntax is disabled.  I think that's OK, though.
Support null_object test doubles with new syntax.
Add yard docs for new methods.
Improve the way we make `expect` available when rspec-expectations is not used.

- Put it in a named rather than anonymous module.
- Allow the syntax to be toggled.
Merge pull request #277 from JonRowe/fix_isolation_of_allow_message_expectations_on_nil

Fix isolation of allow_message_expectations_on_nil
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