circleci.go
func (c *Client) AddEnvVar(account, repo, name, value string) (*EnvVar, error) {
	envVar := &EnvVar{}

	err := c.request("POST", fmt.Sprintf("project/%s/%s/envvar", account, repo), envVar, nil, &EnvVar{Name: name, Value: value})
	if err != nil {
		return nil, err
	}

	return envVar, nil
}
func (c *Client) AddEnvVar(account, repo, name, value string) (*EnvVar, error) {
	envVar := &EnvVar{}

	err := c.request("POST", fmt.Sprintf("project/%s/%s/envvar", account, repo), envVar, nil, &EnvVar{Name: name, Value: value})
	if err != nil {
		return nil, err
	}

	return envVar, nil
}
// AddEnvVar adds a new environment variable to the specified project
// Returns the added env var (the value will be masked)