Bug 958186 - Remove links to /mobile on all states of /new

This  fixes part  of https://bugzilla.mozilla.org/show_bug.cgi?id=920212 and solves https://bugzilla.mozilla.org/show_bug.cgi?id=Bug 958186. We need to change mobile links that point to firefox/fx to firefox/partners before we remove the firefox/fx page.  On the /new/ page we need to change the mobile links to point to the play store.