FroyoSharedPreferenceSaver ignores "backup" parameter

```
FroyoSharedPreferenceSaver and GingerbreadSharedPreferenceSaver take in a 
"backup" parameter but ignore its value, backing up preferences no matter what 
happens.

Expected behavior: avoid backing up preferences if backup == false.
```

Original issue reported on code.google.com by `cow...@bbs.darktech.org` on 13 May 2012 at 5:01
