A11y fixes for pa11y dashboard pages. (#306)

* First draft of a11y fixes.

* Amended results title

* Amended results title (again)

* Back to top keyboard operation

Removed the 'data-role="top"' attribute, which implemented a cool animation to scroll to top but prevented the default behaviour, resulting in the keyboard focus not going back to top.

* Options Button

Fix to have a working options button, but using the mouse only. This is not a good solution because it cannot be operated via the keyboard.

* Fixed options menu css.

* Results view layout changes

* Undoing layout changes

* Graph layout fixes.

* Skip Rules Link

Added a link to skip the list of rules, which can get very long and annoying for any keyboard user not interested in selecting a rule. Most probably, implementing a collapsible list of rules would be a better solution here.

Co-authored-by: Carlos Muncharaz <carlos@muncharaz.eu>

view/partial/task-header.html

@@ -14,7 +14,7 @@ GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with Pa11y Dashboard.  If not, see <http://www.gnu.org/licenses/>.
 }}
-<div class="col-md-12 zfix">
+<section class="col-md-12 zfix">
 	<div class="ruled task-header">
 		<div class="row clearfix">
 			<div class="col-md-12">
@@ -41,4 +41,4 @@ along with Pa11y Dashboard.  If not, see <http://www.gnu.org/licenses/>.
 			</div>
 		</div>
 	</div>
-</div>
+</section>