Use :post-init for go-flymake rather than :features
Add go-errcheck and go-lint to exec-path

Allows both flymake (env PATH) and flycheck (exec-path) to find these programs.
Add :post-init for flycheck-color-mode-line-mode

Enables the mode via flycheck-mode-hook after flycheck is loaded
Add flycheck-cask recipe
Add flycheck-pos-tip recipe
Merge pull request #1731 from dougm/flycheck

Flycheck related recipe enhancements