269 data types

Fix #269 

This pull request fixes the following functionalities:
- Creating new Data Types
- Editing Data Types
- automatically display the correct input fields and help texts for different data_field types

This pull request is on top of #262 because I need the data_objects to test my data types.

[See the compare with #262 ](https://github.com/YaleSTC/shifts/compare/261_data_objects...269_data_types?w=1)

https://github.com/YaleSTC/shifts/compare/b59c172956f01f9294ad6845caf72927e754e0fe...36b02e1397044c6425899e04c7e1b6c5e79bcc90?w=1