Wifi notifications: notify when wifi connects [1/2]

Options:
  off (default)
  a dry white toast
  a notification
  a notification with a sound

For those of us that survive on wifi islands in small college towns this is
pretty nice to have

Any notification within 30 seconds of broadcast intent ACTION_BOOT_COMPLETED
will be canceled to prevent startup notification spamming. 8 (default) of the
previous connections are remembered and it will update the notification's content
accordingly if you've restored a connection.

PS2: fix string WiFi -> Wi\u2011Fi for translations
PS3: strings compatibility for Japanese & wrap at 100 chars per line

Change-Id: I50f00aabad692d2547f4c74bdaaae84947ba84eb