gradle: Use fixed file name for downloaded bnd jar
gradle: Use fixed file name for downloaded bnd jar

The URI provided by the bnd_jar property may not have a valid file name
as the last component of the URI's path. This is true for JPM URLs.

Signed-off-by: BJ Hargrave <3d26bb3930946e3370762d769a073cece444c2d8@bjhargrave.com>

GEBIT/bnd,psoreide/bnd,magnet/bnd,mcculls/bnd,GEBIT/bnd,xtracoder/bnd,lostiniceland/bnd,joansmith/bnd,magnet/bnd,joansmith/bnd,mcculls/bnd,psoreide/bnd,mcculls/bnd,magnet/bnd,lostiniceland/bnd,lostiniceland/bnd,psoreide/bnd,xtracoder/bnd