#48 Add version info in the About dialog

[Nilesh Shah]

The About dialog has only the SaltWater logo image. The
dialog box should also display current version
information and possibly a credit sub dialog box.

Here's my recommendation about the layout -

Just below the image and a line before the "OK" button,
add text "SaltWater 1.0.8" in a mid-zie/large font. Add
a "Credit" button to the left of the "OK" button. On
clicking Credit button opens another dialog box with
some text like "Written By : Adam Lancaster"