don't sanitize number

[afeld]

I haven't looked through all the code, but I think it's better (Principle of Least Surprise-wise) for people to see exactly the number that they put in.

https://github.com/mhs/sms-spec/blob/d93fd847387f5fabc0c03c5363bf8af66ea2cf2a/lib/sms_spec/util.rb

Credit to @monfresh for the idea.

[monfresh]

If anyone is interested, I've fixed this in my fork: https://github.com/monfresh/sms-spec
monfresh@786238c