Fixed two problems

Major fixes:
* Issue https://github.com/lijunjieone/RenameAndroidPackage/issues/2 , caused when the `application` tag (or other tags under it) without `android:name` attribute, added 3 conditionals to avoid accessing non-exist dict property error
* When AndroidManifest.xml has UTF-8 characters (eg. Chinese), a `UnicodeDecodeError: 'ascii' codec can't decode byte XXX in position XXXX: ordinal not in range(128)` error would be thrown, so added unicode convertion for `fixXml.saveXml` method

Minor fixes:
* Minor code refactor, replace strings `"{%s}name"%self.ns_android` with a variable for more clearly. I'm not a Python developer, so not sure this is correct (but I hope so)