Use lowercase "f" for Logger interface functions

[pteich]

This is not a real issue but I would suggest to use a lowercase f for your Logger interface function, e.g. Errorf(string, ...interface{}) instead of ErrorF(string, ...interface{})

This way, it is much easier to use existing logger implementations directly as this is the more or less default in the Go landscape (IMHO). In addition, also the Go stdlib functions like Printf() use it this way.

[wagslane]

fixed in 0.10.0