Refactor router and storage

* Split and extract data-logic from application level
* Move storage to DeeSee package
* Move router into internal package
* Fix Makefile
* Fix documentation
* Fix tests

pkg/deesee/storage/storage.go

@@ -0,0 +1,56 @@
+package storage
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"github.com/eslider/superherohub/pkg/deesee"
+	"os"
+	"strings"
+)
+
+type DeeSee []*deesee.Superhero
+
+// New DeeSee storage.
+func New(path string) (d *DeeSee, err error) {
+	d = &DeeSee{}
+	err = d.Load(path)
+	return
+}
+
+// Load superheroes from json file
+func (s *DeeSee) Load(path string) (err error) {
+	// Read and unmarshal s from  json f path
+	f, err := os.OpenFile(path, os.O_RDONLY, 0644)
+	if err != nil {
+		return fmt.Errorf("unable to read f: %w", err)
+	}
+
+	return json.NewDecoder(f).Decode(s)
+}
+
+// Store superhero
+func (s *DeeSee) Store(hero *deesee.Superhero) (err error) {
+	// Check if superhero superpower is acceptable
+	if !hero.IsAcceptable() {
+		return errors.New(fmt.Sprintf("Hero power is not acceptable: %s", hero.Name))
+	}
+
+	// Prevent to store duplicate superheroes
+	if deesee.FindByName(*s, strings.TrimSpace(hero.Name)) != nil {
+		return errors.New(fmt.Sprintf("Hero already exists: %s", hero.Name))
+	}
+
+	*s = append(*s, hero)
+	return
+}
+
+// FindByName from superheros list
+func (s *DeeSee) FindByName(name string) *deesee.Superhero {
+	for _, hero := range *s {
+		if strings.EqualFold(name, hero.Name) {
+			return hero
+		}
+	}
+	return nil
+}