Settings: Hide storage devices with removed status

Depending on the number of storages added in storage_list.xml, the Storage
Settings can be full of disconnected usb devices. With this change, the
devices with status "removed" are not listed (normally they stand grayed,
requesting you to connect something). If a device has the status
"bad removal" or any other status, it will be listed normally.

Patch Set 2: Fixed code formatting, removed config

Patch Set 3: Fix class name, remove unused imports

Change-Id: Ic429f0d7e62013b8355d6a20bf9394a7b84a8da2
Dont show "Erase SD Card" when there is none

On devices with physcal, external SD Cards, the "Erase SD card"
option in in Settings/Storage is available even when there is
no SD card present, this dont make much sense since you cannot
erase a card that is absent. With this change the erase option
is bound to the mount toggle which leads to the following
consequences:

 Card present and mounted -> Erase enabled
 Card present but unmounted -> Erase enabled
 No card present -> Erase disabled
 Card present and MTP attached -> Erase disabled

Change-Id: I756ae8af3e0565febaf940df5f4991dd89105bd9