Replace custom jquery css with native one. Fixes wrong assets path for calendar in production

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/application.scss

@@ -2,7 +2,7 @@
  * This is a manifest file that'll automatically include all the stylesheets available in this directory
  * and any sub-directories. You're free to add application-wide styles to this file and they'll appear at
  * the top of the compiled file, but it's generally better to create a new file per style scope.
- *= require jquery.ui.gitlab
+ *= require jquery.ui.datepicker
  *= require jquery.atwho
  *= require select2
  *= require highlightjs.min
@@ -43,6 +43,7 @@
 @import "generic/forms.scss";
 @import "generic/selects.scss";
 @import "generic/highlight.scss";
+@import "generic/jquery.scss";
 
 /**
  * Page specific styles (issues, projects etc):

app/assets/stylesheets/generic/jquery.scss

+.ui-widget {
+  font-family: $regular_font;
+  font-size: $font-size-base;
+
+  &.ui-datepicker-inline {
+    border: 1px solid #DDD;
+    padding: 10px;
+    width: 270px;
+
+    .ui-datepicker-header {
+      background: #EEE;
+      border-color: #DDD;
+    }
+
+    .ui-datepicker-calendar td a {
+      padding: 5px;
+      text-align: center;
+    }
+  }
+}

app/assets/stylesheets/main/fonts.scss

 /** Typo **/
 $monospace_font: 'Menlo', 'Liberation Mono', 'Consolas', 'Courier New', 'andale mono', 'lucida console', monospace;
+$regular_font: "Helvetica Neue", Helvetica, Arial, sans-serif;