NEXUS-6310: Align NX mime rules with Tike 1.6

For example, use of app/gzip over older app/x-gzip, etc.
NEXUS-6310: Redo change from 7514b292756b703a6f9916247e8f7581efc676de

As it was not correct. ZIP needs higher priority, as with change
from 7514b292756b703a6f9916247e8f7581efc676de all ZIPs became
app/java-archive's
Related fix: media type registry was rebuilt over and over again

Instead of that, get hold on tika config and build it once and use it
always