add backup warning view to backup flow

src/sass/views/backup-warning.scss

@@ -1,4 +1,4 @@
-#onboarding-backup-warning{
+#backup-warning{
   .warning{
     margin:4rem auto 1rem;
     height: 11rem;
@@ -21,7 +21,7 @@
 }
 
 @media (max-width: 400px){
-  #onboarding-backup-warning{
+  #backup-warning{
     .warning{
       margin: 2rem auto 1rem;
       height: 8rem;
@@ -45,10 +45,10 @@
   }
 }
 @media (max-height: 540px){
-  #onboarding-backup-warning{
+  #backup-warning{
     .cta-buttons{
       float:left;
       position: relative;
     }
   }
-}
+}

src/sass/views/includes/modals/screenshot-warning-model.scss

@@ -1,7 +1,7 @@
 #screenshot-warning-modal{
   .popup-modal-header{
     &-img{
-      background-image: url('../img/onboarding-no-screenshot.svg');
+      background-image: url('../img/no-screenshot.svg');
     }
   }
-}
+}

src/sass/views/onboarding/onboarding.scss

@@ -101,7 +101,7 @@
         max-width: 600px !important;
       }
       button{
-        max-width: 400px !important; 
+        max-width: 400px !important;
       }
     }
   }
@@ -112,6 +112,6 @@
 @import "onboard-tour";
 @import "onboard-collect-email";
 @import "onboard-backup-request";
-@import "onboard-backup-warning";
+@import "../backup-warning";
 @import "onboard-disclaimer";
 @import "onboard-push-notifications";