Create vault and use a single Java style

* Add `create-vault` command
* Rename `remove` to `delete-vault` so we only have one verb meaning remove/delete, which is easier to understand.
* Reorganize the Command enum, methods, case statements, and in README.md so they always occur in this order:
    * upload
    * delete
    * download
    * create-vault
    * delete-vault
    * inventory
    * info
    * list
* Clean up the style in README.md (only use `#`s for headers), more spacing between sections
* Clean up Java style to use this style:
    ```java
    private String myFn(String myString, String anotherString) {
        // Some code

        return anotherString;
    }
    ```
* Add some comments to indicate what each section of code does