Warn, Error and Critical methods now return an error for log4go compatibility
Merge pull request #29 from andrewzeneski/log4go-compat

Error returning for easier migrations from log4go
moved lock above Len() check to prevent a race condition with adding new elements
Merge pull request #31 from andrewzeneski/master

Moved locking to prevent race conditions
Added ANSI n [;k] m sequence format identifier. #32.
Merge pull request #32 from cihub/gs_issue_32

ANSI escape format identifier.