be more consistent about attribute file names:

- attributes.js ALWAYS refers to trace attributes
- layout_attributes.js ALWAYS referes to layout attributes

Author: etpinard

src/components/annotations/attributes.js

@@ -1,6 +1,6 @@
 var Plotly = require('../../plotly');
 var ARROWPATHS = require('./arrow_paths');
-var fontAttrs = require('../../plots/plots/font_attributes');
+var fontAttrs = require('../../plots/font_attributes');
 var extendFlat = require('../../lib/extend').extendFlat;
 
 module.exports = {

src/components/colorbar/attributes.js

@@ -1,5 +1,5 @@
-var axesAttrs = require('../../plots/cartesian/attributes');
-var fontAttrs = require('../../plots/plots/font_attributes');
+var axesAttrs = require('../../plots/cartesian/layout_attributes');
+var fontAttrs = require('../../plots/font_attributes');
 var extendFlat = require('../../lib/extend').extendFlat;
 
 module.exports = {

src/components/legend/attributes.js

@@ -1,4 +1,4 @@
-var fontAttrs = require('../../plots/plots/font_attributes');
+var fontAttrs = require('../../plots/font_attributes');
 var colorAttrs = require('../color/attributes');
 var extendFlat = require('../../lib/extend').extendFlat;