added unicode_literals import at start of each file

erpnext/utilities/transaction_base.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from __future__ import unicode_literals
 import webnotes
 from webnotes.utils import load_json, cint, cstr, flt, get_defaults
 from webnotes.model.doc import Document, addchild, getchildren