Refactoring/rewrite of modal boxes handling

assets/sass/app.sass

@@ -15,7 +15,7 @@
 @import select_dropdown
 @import suggest_menu
 @import dialog_box
-@import popover
+@import modal
 @import pagination
 @import header
 @import logo
@@ -41,6 +41,7 @@
 @import task_board_date
 @import task_tags
 @import task_summary
+@import task_form
 @import task_listing
 @import comment
 @import subtasks