Various improvements

- Corrected class name
- Made selectable item width slightly wider for desktop view
- Changed colours to show disabled states correctly
- Included correct and incorrect colours
- Fixed issue where selectable items had a fixed width when changed to
small and medium devices
- Fixed bug where IE changed disabled selects to a grey font colour,
making it unreadable.

--- NOTE ---
More work might be required on the way the select is working, however
this fix is must better than previous version.
Moved media queries
Merge pull request #5 from zenduo/develop

Various improvements
Merge branch 'develop' of https://github.com/adaptlearning/adapt-contrib-matching into develop

* 'develop' of https://github.com/adaptlearning/adapt-contrib-matching:
  Moved media queries
  Various improvements
  Updated button names and removed conditionals
Removed H6's on buttons / swapped for spans
Merge pull request #6 from zenduo/develop

Removed H6's on buttons / swapped for spans
Merge branch 'develop' of https://github.com/adaptlearning/adapt-contrib-matching into develop

* 'develop' of https://github.com/adaptlearning/adapt-contrib-matching:
  Removed H6's on buttons / swapped for spans
Merge pull request #7 from adaptlearning/develop

Develop