Fix exampple: Remove `rowIndex` from `select_rows` example - not used
Dev: Add comment to rowCallback trigger about undocumented parameters
Dev: Update bootstrap libraries to 3.2
Fix: Example SQL database had extension field as an integer. However, that meant that numbers such as `0001` were not correctly saved
Fix: Numeric sorting for `0` was incorrect

* This fixes DataTables/DataTables #414