ASN1: make File_ASN1 accept int primitives and not just Math_BigInteger objects when an integer is expected

The code to convert the regular integer type into the appropriate format could all just be in-line'd when an integer primitive is used but this approach is easier to read.
ASN1: let strings in as well
Merge pull request #336 from terrafrost/asn1-int

ASN1: make File_ASN1 accept int primitives and not just Math_BigInteger ...

* terrafrost/asn1-int:
  ASN1: let strings in as well
  ASN1: make File_ASN1 accept int primitives and not just Math_BigInteger objects when an integer is expected