Adjusting challenges view translation

- Make "Back to all challenges" button translatable
- Allow some flexibility for the line "#_of_gems gem_icon Prize" - this
is made following the practices with linkstart/linkend implementation
- prize "string" is left as is because used as a placeholder
- code comment "prize" had to be moved 1 line up - before the p (as no
room for it is left inside the p) which however seems OK to me, because
the comments above and below has been made the same way before

common/locales/en/challenge.json

@@ -52,5 +52,7 @@
     "challengedOwnedFilterHeader": "Ownership",
     "challengedOwnedFilter": "Owned",
     "challengedNotOwnedFilter": "Not Owned",
-    "challengedEitherOwnedFilter": "Either"
+    "challengedEitherOwnedFilter": "Either",
+    "backToChallenges": "Back to all challenges",
+    "prizeValue": "<%= gemcount %>&nbsp;<%= gemicon %> Prize"
 }

website/views/options/social/challenges.jade

@@ -106,7 +106,7 @@ script(type='text/ng-template', id='partials/options.social.challenges.html')
               =env.t('challengedEitherOwnedFilter')
       .col-md-10
         a.btn.btn-info#back-to-challenges(ng-show="cid", ui-sref='options.social.challenges', ui-sref-opts='{reload: true}')
-          | Back to all challenges
+              =env.t('backToChallenges')
         // Creation form
         button.btn.btn-success#create-challenge-btn(ng-click='create()', ng-hide='newChallenge')=env.t('createChallenge')
         .create-challenge-from.well(ng-if='newChallenge')
@@ -164,12 +164,8 @@ script(type='text/ng-template', id='partials/options.social.challenges.html')
                 li
                   =env.t('participants', {membercount: "{{challenge.memberCount}}"})
                 li(ng-show='challenge.prize')
-                  p
-                    // prize
-                    | {{challenge.prize}} 
-                    span.inline-block.Pet_Currency_Gem1x
-                    |  
-                    =env.t('prize')
+                  // prize
+                  p!=env.t('prizeValue', {gemcount: "{{challenge.prize}}", gemicon: "<span class='inline-block Pet_Currency_Gem1x'></span>"})
                 li.bg-transparent
                   // leave / join
                   a.btn.btn-sm.btn-danger(ng-show='challenge._isMember', ng-click='clickLeave(challenge, $event)')