deleted duplicate template for maecPackage:Malware_Instance_Object_Attributes that was found in stix_common.xsl (and was identical to the one in stix_to_html.xsl)
updated some of the debugging output to only print when run in debugging mode
for now, do not print "document contents icons" for maec packages/bundles

(this will change when the icons are available)
fixed detection of isRootMaec to also check for root elements for maec packages.

don't display header (aka stix header) for maec documents since there's no corresponding section of the maec doc.