repo: several minor improvements

1. Fix sample content didn't show up when hook doesn't exist.
2. Fix CSS 'word-break' to use 'break-word' not 'break-all'.
3. Fix single quote in 'locale_en-US.ini' file.

models/repo.go

@@ -122,6 +122,7 @@ func NewRepoContext() {
 		log.Fatal(4, "Gogs requires Git version greater or equal to 1.7.1")
 	}
 	git.HookDir = "custom_hooks"
+	git.HookSampleDir = "hooks"
 
 	// Git requires setting user.name and user.email in order to commit changes.
 	for configKey, defaultValue := range map[string]string{"user.name": "Gogs", "user.email": "gogs@fake.local"} {