Expand plugin to highlight Gradle keywords

[cmcginty]

There is another vim-gradle plugin that does a better job of highlight the common Gradle syntax. Is there anyway you could include these features?

http://www.vim.org/scripts/script.php?script_id=5258

[tfnico]

@cmcginty Interesting. The original goal of my plugin was just to apply the standard groovy syntax highlighting to my gradle files, so that plugin seems a much more suitable choice for someone using gradle from vim more intensively. So, please use that one instead, or if you must, PR the syntax highlighting stuff in here and I'll merge it without objections :)