Use X-Requested-With to detect object-subrequest content type

[ameshkov]

X-Requested-With:ShockwaveFlash/23.0.0.207

Migrate to Mac and Android then.

[adbuker]

Also, we should not apply the rule with modifier $object-subrequest to all content-type, i.e., in fact, ignoring it.

[adbuker]

resolved in ADWIN-CR-222