Adds halt_while_performing RSpec matcher
Merge pull request #6 from benedikt/develop

Merges feature: RSpec matcher halt_while_performing
RSpec 2 compatibility for Rspec Matcher halt_while_performing
Matcher::Execution::Base now takes care of RSpec 2 compatibility
Updates version: v0.9.1 -> v0.9.2
Release v0.9.2