Modifications regarding resolving unicode issue and ordering of both prior_node & collection_set elements

1. Files updated regarding unicode issue:
    1) models.py -- save() function
    2) methods.py -- get_common_node_fileds() and get_drawers() functions 

2. Files updated regarding ordering of prior_node & collection_set elements:
    1) models.py -- prior_node_dict() & collection_dict() properties
    2) node_edit_base.html
    3) node_details_base.html