Create .git/hooks directory when it does not exist

[DmitryTsepelev]

Sometimes .git/hooks directory does not exist and lefthook fails to init hooks. The solution is to create the directory when it does not exist.

Closes #158.

[Envek]

You added check for git hooks uninstall. But what about installing?

lefthook/cmd/add.go

Lines 97 to 111 in 04f9b56

	pathToFile := filepath.Join(getGitHooksDir(), hookName)
	if yes, _ := afero.Exists(fs, pathToFile); yes {
	if isLefthookFile(pathToFile) {
	e := fs.Remove(pathToFile)
	check(e)
	} else {
	if yes, _ := afero.Exists(fs, pathToFile+".old"); yes {
	panic("Can`t rename " + hookName + " to " + hookName + ".old File already exists")
	}
	e := fs.Rename(pathToFile, pathToFile+".old")
	log.Println("Existed " + hookName + " hook renamed to " + hookName + ".old")
	check(e)
	}
	}

[DmitryTsepelev]

When lefthook is initialized, it calls DeleteGitHooks, so it guarantees that there was .git/hooks initially. Deleting the folder manually after the init sounds like sam sebe zlobny buratino.

[Envek]

This is so counter-intuitive!

[Envek]

Btw, Travis is failing.

[DmitryTsepelev]

fixed

[skryukov]

I hope we will change it back to os.Mkdir while fixing #90