clean up render mode in status bar
clean up render mode in status bar

"Render on change" or "Render on save" 
should only be shown in the status bar of a relevant file.
Mogztter/atom-asciidoc-preview,wilhelmmatilainen/atom-asciidoc-preview,ldez/atom-asciidoc-preview,asciidoctor/atom-asciidoc-preview