allow any config file name if specified directly (#189)

Currently, we require that config file names end with `.yml` or `.yaml`.
This is because if the user points `-config` at a directory of files, we
only want to use the YAML files in that directory.

But this makes it more difficult to use the `-test -config` option
because config management tools might not have an extension on the file
when preparing a new config file. This change makes it so that if you
point `-config file` directly at a file, it uses it no matter what the
extension is.

config.go

@@ -35,7 +35,7 @@ func (c *Config) Load(path string) error {
 	c.path = path
 	c.files = make([]string, 0)
 
-	err := c.resolve(path)
+	err := c.resolve(path, true)
 	if err != nil {
 		return err
 	}
@@ -234,14 +234,16 @@ func (c *Config) get(k string, v interface{}) interface{} {
 	return v
 }
 
-func (c *Config) resolve(path string) error {
+// direct signifies if this is the config path directly specified by the user,
+// versus a file/dir found by recursing into that path
+func (c *Config) resolve(path string, direct bool) error {
 	i, err := os.Stat(path)
 	if err != nil {
 		return nil
 	}
 
 	if !i.IsDir() {
-		c.addFile(path)
+		c.addFile(path, direct)
 		return nil
 	}
 
@@ -251,7 +253,7 @@ func (c *Config) resolve(path string) error {
 	}
 
 	for _, p := range paths {
-		err := c.resolve(filepath.Join(path, p))
+		err := c.resolve(filepath.Join(path, p), false)
 		if err != nil {
 			return err
 		}
@@ -260,10 +262,10 @@ func (c *Config) resolve(path string) error {
 	return nil
 }
 
-func (c *Config) addFile(path string) error {
+func (c *Config) addFile(path string, direct bool) error {
 	ext := filepath.Ext(path)
 
-	if ext != ".yaml" && ext != ".yml" {
+	if !direct && ext != ".yaml" && ext != ".yml" {
 		return nil
 	}