Fixing Signature Decoding Problem

decodeSig fails on a particular signature in the blockchain due to the assertions of the DER length.

The txid is fb0a1d8d34fa5537e461ac384bac761125e1bfa7fec286fa72511240fa66864d and the signature is in the input sigScript.

This pull request contains the removal of the assertions as well as a unit test illustrating and testing the problem and solution.