Inconsistent refreshManifestCache and manifest files load

[andergmartins]

I just found an inconsistency on installer and refresh manifest function... when installing an extension it gets the first valid manifest xml... ok, but if the file is not mod_xxxx.xml e.g: if the xml file is manifest.xml, the refresh cache will not get it... refresh cache requires a xml file named as extension name, but that file can not exists some times... so I think we should fix that updating the extensions adapters to use the jinstaller findManifest function instead of look for a specific filename... I have fixed it and will make a pull request.

[andergmartins]

There are another places where I think it need to be fixed: com_modules/models/module.php and models/select.php