Fixes #20

- Fixed min-height for inputs and controls
- Inputs, controls and outputs won't overlap
- Build out HTML instead of using fillCol()
- Modified textInputCode() to allow additional items into input-group for library button
- Use input-group instead of form-group for textInputCode()

- Removed knitr parameter
- Add result_only (not in knitr)
- Soft deprecate kntir parameter
- Separate group.css from other css styles