Revert "Remove the message list stars preference now that stars are in the chip"

This reverts commit 48785f52.

Conflicts:
	src/com/fsck/k9/K9.java
	src/com/fsck/k9/activity/Accounts.java
	src/com/fsck/k9/activity/FolderList.java
	src/com/fsck/k9/activity/MessageList.java
	src/com/fsck/k9/activity/setup/Prefs.java