Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/73defe821bfc
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12771 from gtorodelvalle/contacts-bug-925307-intro-exits-search-mode

Bug 925307 - [Contacts] In search mode, clicking INTRO on the keyboard exits the search mode

========

https://hg.mozilla.org/integration/gaia-central/rev/4b88dbcdac2c
Author: Germán Toro del Valle <gtorodelvalle@gmail.com>
Desc: Bug 925307 - [Contacts] In search mode, clicking INTRO on the keyboard exits the search mode

========

https://hg.mozilla.org/integration/gaia-central/rev/cd73bbbe4eeb
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #12759 from fcampo/vcard-x-deprecated-920533

Bug 920533 - [Contacts] Use the mimetype vcard not x-vcard in all the places of the app

========

https://hg.mozilla.org/integration/gaia-central/rev/56eee4ffe759
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Bug 920533 - [Contacts] Use the mimetype vcard not x-vcard in all the places of the app