Add is valid check for a phone number string and multiple regions - #21

Add is valid check for a phone number string and multiple regions#21

StephenPAdams wants to merge 3 commits into

erezak:mastererezak/libphonenumber-csharp:masterfrom

StephenPAdams:masterStephenPAdams/libphonenumber-csharp:masterCopy head branch name to clipboard