Move mixins and variables under gitlab bootstrap

app/assets/stylesheets/gitlab_bootstrap.scss

@@ -8,15 +8,15 @@ $baseLineHeight: 18px !default;
 @import "bootstrap/responsive-1200px-min";
 
 @import "font-awesome";
-@import "variables.scss";
-@import "fonts.scss";
-@import "mixins.scss";
 
 /**
  * GitLab bootstrap.
  * Overrides some styles of twitter bootstrap.
  * Also give some common classes for GitLab app
  */
+@import "gitlab_bootstrap/variables.scss";
+@import "gitlab_bootstrap/fonts.scss";
+@import "gitlab_bootstrap/mixins.scss";
 @import "gitlab_bootstrap/common.scss";
 @import "gitlab_bootstrap/typography.scss";
 @import "gitlab_bootstrap/buttons.scss";