chore(package): update async to version 1.5.2
chore(package): update async to version 1.5.2

http://greenkeeper.io/
bhaskarmelkani/jsforce,pcon/jsforce,jsforce/jsforce,pcon/jsforce,saleswise/jsforce,pcon/jsforce,jdcrensh/jsforce,saleswise/jsforce,jdcrensh/jsforce,jsforce/jsforce,bhaskarmelkani/jsforce,saleswise/jsforce,jsforce/jsforce