(Maint) Provide JUnit output for jenkins

Without JUnit style output we don't have a good way of seeing test
failures within jenkins. This adds a new rake task ci:spec that will
run with junit output, descriptive output and spec order logging.

It turns out that some of the tests would call safe_posix_fork which
ended up closing all open file handles. This ended up also closing the
file handle that rspec would hold open for the junit output formatter.
Those tests have been modified to ensure that the file descripters are
not actually closed.