[NPANDAY-604] simplify assembly extraction

No need to load assemblies for reflection since all necessary information is
available in the assembly name. This also allows multiple versions of
assemblies to be used, since previously the first loaded one would be used
for every assembly with the same simple name.

git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1523534 13f79535-47bb-0310-9956-ffa450edef68