Ubuntu: Imap Settings re-work

The Imap settings page is now part of a tabbed component so we can group
all settings pages together similar to desktop version.

Settings page now validates user input on required username and server
name fields. Presenting red label text

Page now has a toolbar to save settings

So now if the user already has a configured account the first page they
see is the Mailbox view and get prompted for password. The user can still
access settings from the toolbar

Added save.svg, settings.svg and cancel.svg all are from the
ubuntu-mobile-icons package
available from http://packages.ubuntu.com/trusty/all/ubuntu-mobile-
and is available under the CC-BY-SA 3.0. Copyright by 2004-2012,
Canonical Ltd.

REVIEW:117504

Moved setting mailbox sorting preference from imap settings to SettingTabs.qml