Map the Rarity "Basic" back to the old "Common"

 This change is needed due to the fact that the old TP-API used "Common" as second lowest rarity type. The v2 API however uses "Basic".
Correct a message and delete an unused variable.
Merge pull request #155 from keneanung/MapBasicToCommon

Map the Rarity "Basic" back to the old "Common"