For x2many relational fields(of type kanban), we shoud be able to set custom label for
'Create / Add' button by adding 'create_text' node option on particual field from xml.
Right now, 'create_text' is only handled for many2many fields, preventing users to set
custom label for one2many fields.
This commit allows users to set Create Button label for both m2m and o2m fields.
Dharmraj Jhala
b67331fc18