A grocery strike has been averted in Rhode Island and Massachusetts as Shaw’s Supermarkets and the United Food and Commercial Workers came to an agreement this weekend on a new five-year contract. The union says the contract was overwhelmingly approved by members. A federal mediator was called in this weekend as the two sides failed to find common ground, and the potential for a two-state walkout rose on the horizon. The new contract covers 5,200 workers at 38 stores and includes a pay raise and an increase in company contributions to health and retirement benefits.