- add .sidebar-brand-icon class
- align sidebar brand text and icon with flexbox

- rename sidebar-menu-label in sidebar-menu-badge
- add hover for submenu indicator

- add sidebar submenu button and icon color variables for hover and active states
- add sidebar hover link color variables

- rename $brand-primary to $primary to simplify integration with bootstrap 4 beta
- cleanup sizing and positioning for icons and badges
- remove unused badge width and height variables
- rename $sm-element-spacing-x to $sm-inner-spacing-x
- change $sm-spacing-x to apply horizontal spacing to menus instead of buttons
- add $sm-button-spacing-x to apply horizontal spacing to buttons
- make the toggle button indicator icon optional by moving .sidebar-menu-button:not(:only-child):before to a separate element with .sidebar-menu-toggle-icon class
- add .sidebar-menu-icon—left and .sidebar-menu-icon—right spacing modifiers to apply horizontal spacing between buttons icon and text
- add icon sizing utility classes .sm-icons-1 and .sm-icons-small
- cleanup condensed menus
- remove .sm-icons-right utility in favor of adding margin-left: auto to the icons since the buttons are using flexbox
- drop sass-strip-unit dependency
- disable npm lock file
- upgrade dev tools to webpack
- update README
- drop dist/sidebar.min.css in favor of a single dist/sidebar.css file already minified