Revert "route variables should not have underline"

fix#2039 & test

log output format improvement

move log level info ahead to filename info, better readability

update swagger ParameterItems

update swagger define

session.NewManager second params shoube be a object not a string

adds ability to reset params after a filter runs

When a filter is run _after_ the router completes, it's input params,
such as `":splat"` will have been overwritten by the filter's router pass.
This commit adds the ability to tell the router to revert to the previous input
params after running a filter.