By Martin Baccardax A big jump in expenses didn’t hold back Amazon earnings, but the world’s biggest retailer is nonetheless planning to increase the costs of its Prime membership. Amazon Inc (AMZN) – Get Amazon.com, Inc. Report posted stronger-than-expected second quarter earnings Thursday, while unveiling a price increase for its Prime members, as costs for the world’s biggest retail continue to accelerate. Amazon said net income for the three months ending in December was pegged at $14.3 million, or $27.75 per share, nearly double the tally from the same period last year and absolutely crus…