use any go binary in the users environment path
Merge pull request #1 from colekowalski/gopath

use any go binary in the users environment path (At some point we're going to have to make this work on winblows)
fixed goat not running when not in a goat environment
added GOAT_ACTUALGO environment variable option for specifying real go path
moved common.go into its own module
gofmt -w src
added docs on GOAT_ACTUALGO
added mercurial support
Added docs for mercurial.
update makefile to allow for cross-compilation
fixed help text formatting
added fields to GoatEnv and added code docs
made SetupGoatEnv do the actual reading of the Goatfile and parsing its json
fixed IsProjRoot to not be implemented really stupidly
moved deps into env
made goatfile reading be backwards compatible
added setup step to basic run that sets up loopback link if necessary
made FetchDependencies' output much more readable
make goat use full path for itself
go fmt