tab-completion

Tab is not valid when the parent directory case does not match
```powershell
PS /root> tree ./cloudcone-cli/
./cloudcone-cli/
├── cloudcone-cli
├── cloudconecli-zhcn
├── powershell
│   ├── cloudcone-cli1.ps1
│   ├── cloudcone-cli.ps1
│   └── README.md
└── README.md

1 directory, 6 files
PS /root> ./Cloudcone-cli/p <tab>
```
Expected
```powershell
./cloudcone-cli/powershell/
```
