fix specs for rubygems >= 2.0.1

rubygems was trying to reference `FileUtils::Entry_` after we'd replaced
`FileUtils`. Delay the initial swap until `before(:suite)`.
ref: rubygems/rubygems@7b03169c1e4f3efd16d63828a0e2315c488445d9
remove notifications, multiple rvm rubies from guard
tame fog's excon dependency
Release v3.1.2