Replace `javascript:void(0)` with `#`

Fixes:
- issues with content security policy (#1215)
- onbeforeunload in IE (#403)

We don't need to add a preventDefault because all clicks on
.chzn-container already have a preventDefault
No href at all!
When choosing a result in single select mode, set the current value
to false (If it exists, of course).

Fixes #1391
Disable Chosen on iOS devices (iPad, iPod, iPhone)
Only tag mobile as not supported browser
case insensitive
Added anchor tags to documation headers
Added footer to option page
Merge pull request #1392 from harvesthq/single-select-should-unset-current-value

Single select value fix
Make the entire section title a link
Wrapped the text inside of the <h2> tags with anchors, and added
an icon to appear on :hover.
Make the icon be clickable when visible
Indentation/whitespace fixes
Link to the actual license instead of the Wikipedia page
Fix indentation and change link per https://github.com/harvesthq/chosen/pull/1397
remove use of attr(), closes #334
remove href of <a />
use native dom element
enforce pointer cursor for links
Merge remote-tracking branch 'upstream/no-more-js-void' into remove-attr
Update copyright year.