Add message for missing map in Internet Explorer/ MSIE 7/8

* "Unfortunately the map doesn't work in older browsers"
* http://juxtalearn.net/maps-summary-by-country/
* http://whatbrowser.org
PHP compatibility/ code portability - move class instantiations

* Move "new" constructor statements into "JuxtaLearn_Hub" class
* Modified the "JUXTALEARN_HUB_URL" define
Merge github.com:mhawksey/wp-juxtalearn-hub
Fix "JUXTALEARN_HUB_REGISTER_FILE" and ".._URL" defines
Fixing saving/updating of student problems - call parent::save_post function
Make ".juxtalearn-meta" sections stand out more - CSS/ style

* Plus, switch from 'id' to 'class' - bug fix
Merge pull request #4 from IET-OU/master

Code portability, MSIE 8 message, fix editing student problems