[NPANDAY-578] correct order of resolution from GAC

Cleaned up the code that checked the hint path for an existing reference.
Moved the code that checked the GAC until after the HintPath, to better
respect the order used by MSBuild.


git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1451798 13f79535-47bb-0310-9956-ffa450edef68
[NPANDAY-578] factor out resolution methods

This allows the method to be more easily overridden to alter the order, which
is needed in Silverlight projects


git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1451801 13f79535-47bb-0310-9956-ffa450edef68