Issue warning when configuration contains an unrecognized name.

Check cop names and parameter names.
Fix random failure spec

This is about the random failure specs for interruption with Ctrl-C
https://travis-ci.org/bbatsov/rubocop/jobs/6877252

The specs were testing real behavior by running rubocop
as a child process. However it seems to be unstable
and also cannot be measured in coverage report.
So rewrote them to run in thread with some stubs and mocks.
Merge pull request #115 from zeroed/master

#60 : Use the attr family of functions to define trivial accessors or mutators.
Merge pull request #121 from yujinakayama/fix-random-failure-spec

Fix random failure spec
Merge pull request #120 from jonas054/catch_errors_in_config

Issue warning when configuration contains an unrecognized name.
Add new cop LeadingCommentSpace
Add new cop SemicolonMethodCall
fixing Nil bug in TrivialAccessor cop