BUG: Right format for password from Curses

Reading the password from Curses Blinkenlights returns a bytes objects
instead an utf-8 string.

This patch will decode if bytes is provided.

Closes: #49

Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>

offlineimap/ui/Curses.py

@@ -583,6 +583,10 @@ class Blinkenlights(UIBase, CursesUtil):
         finally:
             self.unlock()
             self.inputhandler.input_release()
+
+        # We need a str password
+        if isinstance(password, bytes):
+            return password.decode(encoding='utf-8')
         return password
 
     def setupwindows(self, resize=False):