[minor] rename icons as per FontAwesome 4 (#7136)

diff --git a/erpnext/accounts/page/pos/pos.json b/erpnext/accounts/page/pos/pos.json
index 31c043c..abd918a 100644
--- a/erpnext/accounts/page/pos/pos.json
+++ b/erpnext/accounts/page/pos/pos.json
@@ -3,7 +3,7 @@
  "creation": "2014-08-08 02:45:55.931022", 
  "docstatus": 0, 
  "doctype": "Page", 
- "icon": "icon-th", 
+ "icon": "fa fa-th", 
  "modified": "2014-08-08 05:59:33.045012", 
  "modified_by": "Administrator", 
  "module": "Accounts",