Added footer + styles for footer.

Also added less/kb/ with kb specific styles, and overriding boodstraps variables in styles.css
Bugfix (minor): Fixed typo bug.
Moved footer margin definition into less/kb/variables.less
Wrapped all footer col-* into row elements.
Minor: Fixed indentation.
Merge pull request #4 from Det-Kongelige-Bibliotek/footer

Footer html + styles