add remove method to base
add remove method to base

ramakrishnan/node-db-migrate,db-migrate/node-db-migrate,SamuelBolduc/node-db-migrate,marbemac/node-db-migrate,vertiman/node-db-migrate,chatter/node-db-migrate,cqricky/node-db-migrate,ror/node-db-migrate,ViGo5190/node-db-migrate,bwiggs/node-db-migrate,MForMarlon/node-db-migrate,db-migrate/node-db-migrate,andela-ooladayo/node-db-migrate