A slight difference in height between the previous and next buttons
was causing the next button to appear to move when switching between
a page with or without the previous button.
Ensure that the previous and next buttons have a consistent height and
do not move when switching pages in the onboarding process.
Rather than using relative paths for css imports - which can break when
we move files around - add our styles path to the webpack sass-loader
loader using the `includePaths` setting.
Tom Kirkpatrick
Jack Mallers