Revert "Hack for getting stdout, stderr, exit status in 1.8"

SSH with pty merge stderr to stdout, so do same thing with local exec.

This reverts commit 043e769aa6e656f8034e7cac839b5e8e549b5a1a.

Conflicts:

	lib/serverspec/backend/exec.rb
Set command and its stdout/stderr to example.metadata

In ssh access with pty, stderr is merged to stdout.So serverspec also merge stderr to stdin in exec backend for the integrity.

See http://stackoverflow.com/questions/7937651/receiving-extended-data-with-ssh-using-twisted-conch-as-client
Show command and its stdout when be_reachable fails
Override RSpec::Matchers::DSL::Matcher.failure_message_for_should

To save a step to write failure_message_for_should in each matcher.
Set example to instance variable to set command and its result to it

This is for showing command and its result with failure_message
Override failure_message_for_should in serverspec.rb, so this code is not needed anymore.
Fix because it is not needed to capture the string with regexp
Merge pull request #88 from mizzy/set-failure-message

Show the command and its stdout message when fails