clean unused variables/import

MarkdownLivePreview.py

@@ -1,7 +1,5 @@
 # -*- encoding: utf-8 -*-
 
-import sys
-import os.path
 import sublime
 import sublime_plugin
 

sample.md

@@ -10,3 +10,4 @@ Hope you'll enjoy using MarkdownLivePreview!
 
 [GitHub](https://octodex.github.com/images/jetpacktocat.png)
 
+this is a test

setting_names.py

@@ -5,5 +5,4 @@ PREVIEW_ID = 'markdown_live_preview_id'
 IS_PREVIEW = 'is_markdown_live_preview'
 IS_HIDDEN = 'is_hidden_markdown_live_preview'
 MD_VIEW_ID = 'markdown_live_preview_md_id'
-JUST_CREATED = 'markdown_live_preview_just_created'
 PREVIEW_WINDOW = 'markdown_live_preview_window'