replace GOPATH env var lookups with getGOPATH func throughout codebase

cmd/ponzu/options.go

@@ -14,11 +14,14 @@ import (
 
 func newProjectInDir(path string) error {
 	// set path to be nested inside $GOPATH/src
-	gopath := os.Getenv("GOPATH")
+	gopath, err := getGOPATH()
+	if err != nil {
+		return err
+	}
 	path = filepath.Join(gopath, "src", path)
 
 	// check if anything exists at the path, ask if it should be overwritten
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
+	if _, err = os.Stat(path); !os.IsNotExist(err) {
 		fmt.Println("Path exists, overwrite contents? (y/N):")
 
 		answer, err := getAnswer()
@@ -67,7 +70,10 @@ func getAnswer() (string, error) {
 }
 
 func createProjectInDir(path string) error {
-	gopath := os.Getenv("GOPATH")
+	gopath, err := getGOPATH()
+	if err != nil {
+		return err
+	}
 	repo := ponzuRepo
 	local := filepath.Join(gopath, "src", filepath.Join(repo...))
 	network := "https://" + strings.Join(repo, "/") + ".git"
@@ -76,7 +82,7 @@ func createProjectInDir(path string) error {
 	}
 
 	// create the directory or overwrite it
-	err := os.MkdirAll(path, os.ModeDir|os.ModePerm)
+	err = os.MkdirAll(path, os.ModeDir|os.ModePerm)
 	if err != nil {
 		return err
 	}

cmd/ponzu/usage.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
-	"os"
 	"path/filepath"
 	"time"
 )
@@ -180,7 +179,10 @@ func ponzu(isCLI bool) (map[string]interface{}, error) {
 
 	info := filepath.Join("cmd", "ponzu", "ponzu.json")
 	if isCLI {
-		gopath := os.Getenv("GOPATH")
+		gopath, err := getGOPATH()
+		if err != nil {
+			return nil, err
+		}
 		repo := filepath.Join(gopath, "src", "github.com", "ponzu-cms", "ponzu")
 		info = filepath.Join(repo, "cmd", "ponzu", "ponzu.json")
 	}