SGS2 + CM9: Flash 9.1.0 Release

CM 9.0.0 stable release was in fact, stable. One small issue though, was that it was unable to detect media files under /sdcard/Notifications or /sdcard/Ringtones (requires a reboot in order for it to be selected as a ringtone/notification tone). Edit: CM 9.1.0 release fixed this.

1. Too lazy to create a nandroid backup this time. My last backup was made from CWM Recovery. No more using ROM Manager!
2. Reboot into CWM Recovery. Note: Already copied cm-9.1.0-galaxys2.zip to internal SD card earlier, and verified MD5 hash too (963f5d56b376dedcaaa55dc3fe967561).
3. install zip from sdcard > choose zip from internal sdcard > cm-9.1.0-galaxys2.zip > Yes.
4. wipe cache partition.
5. advanced > Wipe Dalvik Cache.
6. reboot system now.