Added fread tests; closes #2747
Added fread tests; closes #2747

jangorecki/data.table,jangorecki/data.table,vlulla/data.table,Rdatatable/data.table,Rdatatable/data.table,vlulla/data.table,Rdatatable/data.table,jangorecki/data.table,jangorecki/data.table,vlulla/data.table,Rdatatable/data.table,vlulla/data.table