As Golang supports getting usernames via the standard library, this function
is now used to get the username if the environment variables are empty.
Using the standard library as a fallback is intended to keep compability
to existing implementations that rely on the environment variables dictating
the current username.
* conf: add tests for utils.go
* conf: add tests for static.go
* mock os/exec
* Run tests on Windows
* appveyor: fix gcc not found
* computed: add unit tests
* log: add unit tests
* log: fix tests on Windows
* conf: add some tests
* Finish adding tests
* Cover more cases
* Add tests for testutil
* Add more tests