change api ver to 28.0
change api ver to 28.0

parthiban019/jsforce,pcon/jsforce,lkatney/jsforce,bhaskarmelkani/jsforce,parthiban019/jsforce,bhaskarmelkani/jsforce,jsforce/jsforce,polidog/jsforce,nutthawan/jsforce,jsforce/jsforce,pcon/jsforce,jdcrensh/jsforce,nutthawan/jsforce,jsforce/jsforce,joeferraro/jsforce,joeferraro/jsforce,lkatney/jsforce,saleswise/jsforce,jesperkristensen/jsforce,rdietrick/jsforce,stomita/node-salesforce,jesperkristensen/jsforce,saleswise/jsforce,saleswise/jsforce,pcon/jsforce,kimchouard/jsforce,jdcrensh/jsforce