Update PUI import SCSS

Resolves #857

Author: oodamien

ui/src/scss/pui.scss

@@ -6,7 +6,6 @@
 @import '../../node_modules/pivotal-ui-git-clone/src/css/colors/colors';
 @import '../../node_modules/pivotal-ui-git-clone/src/css/iconography/iconography';
 @import '../../node_modules/pivotal-ui-git-clone/src/css/panes/panes';
-@import '../../node_modules/pivotal-ui-git-clone/src/css/backgrounds/backgrounds';
 @import '../../node_modules/pivotal-ui-git-clone/src/css/select/select';
 @import '../../node_modules/pivotal-ui-git-clone/src/css/forms/forms';
 @import '../../node_modules/pivotal-ui-git-clone/src/css/tables/tables';