regexs for getting packageName and versionCode from filenames

regexs for getting packageName and versionCode from filenames

This is useful for parsing APK files, which can include packageName,
versionCode, and optionally 7 char signing key ID (i.e. <sig>).
This also can set the packageName and versionCoe for non APK files, so
that it is easy to assign them to metadata files, and to allow for
upgrades by setting the versionCode in the filename.