(maint) Remove monkey patch

Prior to this patch, running spec tests with ruby 2.x
would result in deprecation warnings like so:

/Users/kylo/.rbenv/versions/2.1.0/lib/ruby/2.1.0/delegate.rb:343: warning: IO#lines is deprecated; use #each_line instead

This patch removes the monkey patching that led to those
warnings, and simply changes the code to use each_line rather
than lines, which is apparently supported in all the ruby versions
from 1.8.5 to 2.x.