Updated the DropdownComponent.cs and DropdownControl.cs to enable
multiple selection.

Updated the TextBoxControl.cs and PasswordBoxControl.cs to enable
HTML5/CSS3 placeholder attribute.

Signed-off-by: TheMouster <classified.development@gmail.com>
Finished up adding the placeholder attribute to the text and password
boxes.

Signed-off-by: TheMouster <classified.development@gmail.com>
minor stuff