Decrypt a password from BASE64

The fglpass tool can decrypt a BASE64 encoded and encrypted password using a RSA private key.

The fglpass tool uses the RSA private key that was used to encrypt it or that is associated to a certificate containing the public part of that private key.

To decrypt a BASE64 encoded and encrypted password from a RSA private key, enter:
```
fglpass -d -k RSAPriv.pem
```
If the RSA key is protected with a password, you are prompted to enter that password (the password is not displayed to the console while being typed).
```
Enter pass phrase for RSAPriv.pem:
```
You are prompted to enter the BASE64 encoded and encrypted password you want to decrypt.
```
Enter password :Pzk/fNRhetdJDZz5kjNg7P0XET4XsW6bys/fi0
DvugxRPh9d/s41oAws65JY0EPb2zytQjxZ/dwaaRzJPYoQmA==
```
The fglpass tool outputs the password in clear text on the console.
```
hello
```