Encode the frame URL when constructing the hyp.is link

If the URL is not encoded, a frame URL such as
"http://example.com/foo&bar=baz" will generate the page share link
"https://hyp.is/go?url=http://example.com/foo&bar=baz" where the
"&bar..." part becomes a separate parameter instead of part of the "url" param.

src/sidebar/components/share-dialog.js

@@ -10,7 +10,7 @@ function ShareDialogController($scope, $element, analytics, store) {
       return;
     }
 
-    self.sharePageLink = 'https://hyp.is/go?url='+frames[0].uri;
+    self.sharePageLink = 'https://hyp.is/go?url=' + encodeURIComponent(frames[0].uri);
   }
 
   var shareLinkInput = $element[0].querySelector('.js-share-link');

src/sidebar/components/test/share-dialog-test.js

@@ -25,10 +25,11 @@ describe('shareDialog', function () {
 
   it('generates new share link', function () {
     var element = util.createDirective(document, 'shareDialog', {});
-    fakeStore.frames.returns([{ uri: 'http://example.com' }]);
+    var uri = 'http://example.com';
+    fakeStore.frames.returns([{ uri }]);
     element.scope.$digest();
     assert.equal(element.ctrl.sharePageLink,
-      'https://hyp.is/go?url=http://example.com');
+      'https://hyp.is/go?url=' + encodeURIComponent(uri));
   });
 
   it('tracks the target being shared', function(){