[Android] Naming refine for packaging tool

First, the new w3c manifest spec requires accepting any string to be application name.
However in previous make_apk process, they were treated as invalid input.
Second, in the past time, this part of logic is always buggy and
each sub process is validating and modifying the name passed by.
It's a good time to consolidate all these codes and validate the name at beginning,
to produce all necessary strings (transferred from the input name)
for all purposes during the make apk process.
If the package is None, the app_name still need a default name, otherwise we should set a default name for package. I think it's easy to fix after 'FIXME(jinbang): package name should never be generated for developer'