Added support for passing build flags to GoBuild
Move autocommands to plugin/go.vim. Fixes #238
More cleanup related to issue https://github.com/fatih/vim-go/issues/222

 - extracted the code to detect the "default" GOPATH into it's own
   function;
 - expand() automatically takes care of trailing slash if given, this
   allowed to remove the explicit check for trailing slash (which
   remained non cross platform friendly);
 - this allowed GoBinPath() to be nicely cleaned up. Plus the new
   functions may be used in other places.
Merge pull request #239 from gcmt/fix-autocommands

Move autocommands to plugin/go.vim.
Merge pull request #240 from alexaandru/222-more-cleanup

More cleanup related to issue https://github.com/fatih/vim-go/issues/222
Merge pull request #237 from alexaandru/231-build-flags

Added support for passing build flags to GoBuild
Fixes https://github.com/fatih/vim-go/issues/241
Merge pull request #242 from alexaandru/241-errcheck-fix

Fixes https://github.com/fatih/vim-go/issues/241