v1.6.0

• chore(package): add on finish to listen on response finish event (18521af)
• chore(release): 1.6.0 (425a935)
• test(logger): more asset in record result (981eb3e)
• test(logger): remove before and after each by initial app by each test itself (076c626)
• test(logger): test on throw error should still logger (560bd58)
• feat(logger): add duration result to meta (2049ddb)
• feat(logger): add koa res serializer (dff23e4)
• feat(logger): add started_at and req.length, replace originalUrl by href (d9840e0)
• feat(logger): use on-finished to get final response result (a21cfc2)
• feat(logger): use util.format as template to generate logger msg (399cf24)