Move all instances of 'verify identity' to 'show identity'

As discussed in standup this morning - only the act of verifying or a
statement about current status should use that word 'verify.'

FREEBIE

background.html

@@ -85,7 +85,7 @@
                   {{/group}}
                   {{^group}}
                       <li class='end-session'>{{ end-session }}</li>
-                      <li class='verify-identity'>{{ verify-identity }}</li>
+                      <li class='show-identity'>{{ show-identity }}</li>
                   {{/group}}
                   <li class='disappearing-messages'>{{ disappearing-messages }}</li>
                   <li class='destroy'>{{ destroy }}</li>