Data refresh updated to number type with minimum

- HTML template updated to change refresh input element to be of "number" type and specify min value to allow Angular to validate against when used in a form
- Directive updated to change default value for refresh
- translation.json updated to change the units to minutes
- e2e test HTML updated to reflect current layout of a widget
- e2e test updated to use new default value for refresh
Merge pull request #40 from stulees/chore/refresh-update

Data refresh updated to number type with minimum