Don't download line items if we're just looking for totals
Merge branch 'mainrepo_master' into dont-download-line-items-unless-we-have-to

Conflicts:
	Gemfile.lock
	lib/xero_gateway/line_item_calculations.rb
Merge pull request #48 from nikz/dont-download-line-items-unless-we-have-to

Don't download line items if we're just looking for totals