Forms feedback

[dariye]

@andela-cvundi

• Update documentation to use proper button classes.
• Remove extraneous class overrides e.g btn--full-width
• Use grid to determine content width i.e remove one-whole from form buttons.
• To center a .grid__item {}, create a utility class under components i.e source would be src/components/_utilities.scss
• Update notifications class to include border-radius of 4px -- $base-border-radius (src/base/_variables.scss)
• Make select dropdown should have the same height as input fields
• Add border radius to fields. i.e should be 4px.
• Add padding to input text field
• Fix multi-select field style
• Add search field
• Add form fields with icons
• Add padding to checkbox, radio buttons, toggle.
• Add a slider.