accounts: let the daemon removing accounts files

The daemon already flush the directory when removing accounts.
Moreover, getAccountsList() can fail and if it's the case, all
accounts are removed. This is dangerous!
Finally, when dbus fails, this can create dumb directories with
the error as a name. This patch avoid this case.

Change-Id: Ib74604f39adb9c2ba094c45a3f77a8d96ecb613c