account: add password change modal in settings

A button is added in the Ring account setting panel which trigger a
sliding modal enabling a user to change the password used to encrypt
the master key archive (its Ring “account”).

To prevent mistakes, the old password is not required if we know that
there isn't any. The new password is also asked twice for confirmation.

Change-Id: Ibbc0a87f1d108b7fdb66382e8f8f491461eeaccf
Reviewed-by: Kateryna Kostiuk <kateryna.kostiuk@savoirfairelinux.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b2265bb..fb7bde7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -170,6 +170,8 @@
    src/AccBannedContactsVC.mm
    src/MessagesVC.h
    src/MessagesVC.mm
+   src/PasswordChangeWC.h
+   src/PasswordChangeWC.mm
 )
 
 SET(ringclient_BACKENDS
@@ -262,6 +264,7 @@
    ContactRequestList
    ContactRequest
    AccBannedContacts
+   PasswordChange
 )
 
 # Icons