Deletes all content in the rmaven
cache. This should not be necessary, but
never say never, and if there is really a problem with the cache, then
deleting it may be the best thing. This will wait for confirmation from the
user. If running unattended the options("rmaven.allow.cache.delete"=TRUE)
must be set for the action to occur, otherwise it will generate a warning and
do nothing.
clear_rmaven_cache()
nothing, called for side effects