Der default values

DER encoder should not include values that are equual to defaults.

Ref http://luca.ntop.org/Teaching/Appunti/asn1.html:

    DER encoding. Constructed. Contents octets are the same as the BER
    encoding, except that if the value of a component with the DEFAULT
    qualifier is the default value, the encoding of that component is not
    included in the contents octets.
I think this check isn't doing exactly what you want it to do. I.e. it only handles a case where the default data came through the declaration, but what if this kind of data was supplied by the user?

Also, please fix the style: I'm using 2-space indent everywhere and `if (...) {`