Description of problem:
Deploying VIA UI, it is possible to change a textbox setting to whatever because UI does not take constraints into considerations.

Version-Release number of selected component (if applicable):


How reproducible:
100%


Steps to Reproduce:
1. Via UI open a plan and navigate to settings.
2. Select a constraint setting that has a textbox input and change it to something outside of the constraint
3.click on save.

Actual results:
Setting was saved.


Expected results:
Setting outside the constraint cannot be saved.


Additional info:
Tested with "flowers" on the ceiloemter debug setting.

  CeilometerDebug:
    default: ''
    description: Set to True to enable debugging Ceilometer services.
    type: string
    constraints:
      - allowed_values: [ '', 'true', 'True', 'TRUE', 'false', 'False', 'FALSE']