Handle new "No root element" error from REXML

[kiskoza]

Closes #84

[mattwd7]

this seems kinda brittle – if the error message changes, this will require update again. I think instead we want to get ahead of this error if the error-provoking conditions are met, e.g.

Suggested change

	def self.parse(xml)
	parser.parse(xml)
	rescue REXML::ParseException => e
	return {} if e.message.match?(/^Malformed XML: No root element/)
	raise e
	end
	def self.parse(xml)
	return {} if xml.blank?
	parser.parse(xml)
	end

[kiskoza]

Unfortunately blank? is not pure Ruby, it's coming from ActiveSupport. xml.strip == '' should do fine, wdyt?

[mattwd7]

sgtm 🙂