Revise the download and match logic so more motors are downloaded correctly. The...

Revise the download and match logic so more motors are downloaded correctly.  The DownloadResponse now holds on to all the results supplied from Thrustcurve so we can process them a little better.  The TCMissingMotorDownloadAction chooses the motor which has the best match (giving preference to matching digest, desgination and finally RockSim files).  The TCSearchAction records into the database all the motors which have a unique designation.

git-svn-id: https://openrocket.svn.sourceforge.net/svnroot/openrocket/trunk@435 180e2498-e6e9-4542-8430-84ac67f01cd8