fix for issue 270: a path containing .go is no longer evaluated as hidde...

Tracking the problem described in  #270 I found this was caused by the go path (e.g. ~/.go/src/smartystreets/goconey) being interpreted as a hidden directory and therefore not marked as *active*. 

Only changes from active files or directories get tracked. This resulted in all changes being ignored.

This fix changes *isHidden()* to make it accept '.go' as a valid, not hidden section, of a path.

This works on my mac, but I'm not sure if this is the correct way or will work on other platforms. ;-)