Removing black .alert color

Use darker variations of alerts to meet color contrast ratios for
WCAG AAA.
typo fix
bootstrap-accessibility.css: add spaces before open-braces
Merge pull request #10 from cvrebert/patch-1

bootstrap-accessibility.css: add spaces before open-braces
Fixes issue#11 removing whitespaces from css
merge color contrast fix with suggestion from Dennis
Merge branch 'master' into gh-pages