[hotfix] convert number format to basestring before importing. (#3767)

* convert numbers to basestring for link field

* Update importer.py

frappe/core/page/data_import_tool/importer.py

@@ -133,6 +133,9 @@ def upload(rows = None, submit_after_import=None, ignore_encoding_errors=False,
 								elif fieldtype in ("Image", "Attach Image", "Attach"):
 									# added file to attachments list
 									attachments.append(d[fieldname])
+								elif d[fieldname] == 'Link':
+									# as fields can be saved in the number format(long type) in data import template
+									d[fieldname] = cstr(d[fieldname])
 							except IndexError:
 								pass