Doc improvements don’t need a changelog entry.

They just add noise to the changelog.

[ci skip]
describe parameters can now be classes without error
added spec to test new behavior
separate context added for description metadata test
Merge pull request #1636 from nicklink483/fix_metadata_build_description_from

describe parameters can now be classes without error
changelog for #1636
Merge pull request #1616 from rspec/fix_exclusion_priority_for_working_directory

Ignore working directory when excluding system patterns.
changelog for #1616
Remove unneeded requires in rake task.

- rspec/core/version require was added in
  390392e7e76429bbeddedd615565e858c70194f9 but
  looks like it was never actually used.
- We used to have some warnings emitted by the rake
  task (and thus needed to load that support) but
  don’t have any more warnings.
Address ruby warning.

spec/rspec/core/hooks_spec.rb:197: warning: ambiguous first argument; put parentheses or even spaces
Remove /gems/ from default backtrace exclusion patterns.

As discussed in #1536 and #1554, the failure can often be in a gem.

We may add an additional gem filtering API later on but for
now I just want to try this on a few projects and see how the
experience is.
update rake task docs with note about LoadError
Merge pull request #1642 from rspec/update_rake_task_docs

Update rake task docs with note about LoadError
Add placeholder for code_or_symbol to NullColorizer
Merge pull request #1640 from rspec/make-rake-task-more-light-weight

Remove unneeded requires in rake task.
Changelog for #1640.

[ci skip]
Merge pull request #1637 from tomykaira/fix_wrap_args

Add placeholder for code_or_symbol to NullColorizer
changelog for #1637
Merge pull request #1641 from rspec/tweak-backtrace-formatter

Remove /gems/ from default backtrace exclusion patterns.
Allow rspec-core to be used without -expectations or -mocks.

At the moment if one wants to use RSpec's runner in standalone mode one
must first disable the default mocking/expectation adapters.

This patch silently sets up no mocking or expecting framework if the
default configuration is used but only 'rspec-core' is present in the
Gemfile.