Update HTTPStreamingHLSIndexHandler.as

AES Key - fix relative patch issue. With relative key url plugin was downloading it from same location as "plugin.swf" (url was simply "key.dat" but should be full absolute). Correctly it should download it of course from same location as m3u8 playlist file. 
Adding absolute patch is based on code from line 200 (only 1 line).
Merge pull request #52 from Alekscs/patch-1

Update: add absolute patch to key url (AES, only 1 line)