Add fields to AccountType for the new "invite" feature

- Add two attributes, inviteContactActivity and inviteContactActionLabel,
to the contacts.xml file, in addition to the existing ones such as
editContactActivity.

e.g.
<ContactsAccountType
    xmlns:android="http://schemas.android.com/apk/res/android"
    inviteContactActivity="com....editor.InviteContactActivity"
    inviteContactActionLabel="@string/invite_action_label">

- Add two methods to AccountType to obtain the new attributes.
(getInviteContactActionLabel() will return a localized string)

- Add AccountTypeManager.getInvitableAccountTypes() which returns
AccountType's which define the invite activity and have one or more account.

Change-Id: I545b47a7e4957765684314870739085ea0355a98
8 files changed