Integrate URL Field component into Font Picker

- Update bower with new bootstrap-form-helpers tag 2.3.3-rv, bootstrap 3.1.1-rv, and widget-settings-ui-components
- Using the jQuery plugin of URL Field from widget-settings-ui-components in the font picker test file
- Updated font picker jQuery plugin to use URL field and replaced all logic where necessary
- Updated font picker template to implement use of URL field and updated alert message when validation fails