rename Settings.java to BlogPreferences.java

Hopefully this will begin to help clear up the distinction between
"Preferences" and (now) "BlogPreferences".

git-svn-id: https://android.svn.wordpress.org/trunk@954 a6565c4b-a94d-4d28-bb26-aa9e5ab542c0
settle on "settings" for user-facing label

This seems to be consistent with what Android itself does... to use the
name "preferences" internally for activity names and such, but to use
the name "settings" for all user-facing strings.

git-svn-id: https://android.svn.wordpress.org/trunk@955 a6565c4b-a94d-4d28-bb26-aa9e5ab542c0