remove utils.py file; use a setting file for delay between updates

utils.py contained two functions. One which wasn't used, and another,
get_settings() which I moved to MarkdownLivePreview.py

Add an entry to the command palette to edit the settings

MarkdownLivePreview.sublime-settings

@@ -0,0 +1,4 @@
+{
+	// minimum number of milliseconds to wait before updating the preview again
+	"delay_between_updates": 100
+}