Merge branch 'master' into charges_and_taxes
add category to taxes
Merge branch 'master' into charges_and_taxes

Conflicts:
	app/models/invoice.rb
UBL invoice with exemption taxes
adds facturae exemption comments
Test UBL and facturae charges
improve company form for taxes
Merge branch 'charges_and_taxes' of github.com:descala/haltr into charges_and_taxes
more ubl tests
Merge branch 'charges_and_taxes' of github.com:descala/haltr into charges_and_taxes
tax code = percent _ category
fix add taxes link
copy tax comment if tax is exempt
remove unused method
guess tax categories for existing taxes
fix add_category_to_taxes migration
set category on default taxes
remove 4% tax by default
fix test
allow lines without taxes