Fixed a problem where default: "1000000000" in time.Duration was equal to "0".

[UNILORN]

In v1.1.0, setting default: "1000000000" for time.Duration was equivalent to "1s".

but, In v1.2.0, setting default: "1000000000" for time.Duration is equivalent to "0".

I have made the fixes in this Pull Request. #18
Please check it out as it is a necessary fix for the project I am using.

@mcuadros