file synchronization/updating failing

ok, I just want to preface this by saying it's one of those awful errors that seem to be OS dependent, and exactly how it manifests itself is seemingly random.
the error is that for some zites (a steadily climbing amount) I can't sync/update all files, I looked through the debug log and found that this error seems to be related and affect a large number of files ( or the same ones many times)
`[2017-05-04 17:21:04,513] ERROR Site:1MeFqF..q7nH Json merged-ZeroMe/12h51ug6CcntU2aiBjhP8Ns2e5VypbWWtv/data/users/1BR2d8kCqCBaFWLQ9KXnNbJzLmcPJ3DdTL/data.json load error: OperationalError: attempt to write a readonly database in SiteStorage.py line 234 > MutePlugin.py line 100 > SiteStorage.py line 74 > Db.py line 323 > DbCursor.py line 49`

attached is my entire debug log, hope to have this resolved soon.

[debuglog.txt](https://github.com/HelloZeroNet/ZeroNet/files/977387/debuglog.txt)

Start with the attached debug log and trace the reported call chain through SiteStorage.py, MutePlugin.py, Db.py, and DbCursor.py, focusing on the readonly database error. Reproduce the synchronization failure across the affected files and verify that updates complete without the reported OperationalError.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.