[MxitUser] Migrated sql command/queries from PDO to wpdb (Wordpress DB object).
[single-kzm_book] Added check for nset mxpress options for service URL.
[functions_books] Add the function kzm_getExternalReferences() to handle the json service call.
[single-kzm_book] used the method kzm_getExternalReferences() from function_books file to consume json service.
[single-kzm_chapter] Added check in file that renders the chapter, tests to see if user has purchsed the item.
Merge pull request #4 from MongeziNombewu/features/improvements-for-everegg

Migrated from PDO to wpdb in Mxit User