Remove percent placeholder from themes

The vim renderer now handles searching and replacing of the percent
placeholder internally so percent signs can be used directly in themes
and segments instead of the percent placeholder.

Refs #127.

powerline/config_files/themes/vim/default.json

@@ -69,7 +69,7 @@
 				"name": "line_percent",
 				"args": { "gradient": true },
 				"priority": 30,
-				"after": "",
+				"after": "%",
 				"rjust": 4
 			},
 			{

powerline/renderers/vim.py

@@ -15,7 +15,7 @@ vim_setwinvar = vim_get_func('setwinvar')
 
 class VimRenderer(Renderer):
 	'''Powerline vim segment renderer.'''
-	PERCENT_PLACEHOLDER = u''
+	_PERCENT_PLACEHOLDER = u''
 
 	def __init__(self, *args, **kwargs):
 		super(VimRenderer, self).__init__(*args, **kwargs)
@@ -34,13 +34,16 @@ class VimRenderer(Renderer):
 		if current:
 			mode = vim_mode()
 			theme = self.get_theme()
-			segments = [segment for segment in theme.get_segments()]
+			segments = []
+			for segment in theme.get_segments():
+				segment['contents'] = segment['contents'].replace('%', self._PERCENT_PLACEHOLDER)
+				segments.append(segment)
 			self.window_cache[window_id] = (theme, segments)
 		else:
 			mode = 'nc'
 			theme, segments = self.window_cache.get(window_id, (None, None))
 		statusline = super(VimRenderer, self).render(mode, winwidth, theme, segments)
-		statusline = statusline.replace(self.PERCENT_PLACEHOLDER, '%%')
+		statusline = statusline.replace(self._PERCENT_PLACEHOLDER, '%%')
 		return statusline
 
 	def hl(self, fg=None, bg=None, attr=None):