Add support for selling from non-EU countries

[telmich]

We (ungleich.ch) are interested in using this module with residency in CH. Basically the rule set that applies is:

• CH to CH sale: 7.7% at the moment (8% before) for B2C and B2B
• CH to EU: as defined by EU rules
• CH to UK: a) no VAT b) VAT similar to EU rules - we got contradicting information from the UK government about this. One person claims it's like (b), their website says otherwise if you are under a certain revenue limit.
• CH to non-EU-non-UK: 0%
• non-EU,EU to CH: (to be verified): 0%

I believe that CH as a non-EU country could become a sample of a standard case for trading from outside the EU, as I suspect that ruleset for other countries are very similar.

Are you open for integrating non-EU rules into this module, too?