Add support for Windows installers.
Fix Windows idempotency issues & add proxy support

The DisplayName value was incorrect in the window_package call.
This has been corrected, however in doing so we have identified
a bug in the installer which may force us to have to check for
two different DisplayName values in the future.

Added support to the varfile for proxies as this is a commonly
used feature.
Fix copy/paste error in README.md
Document ['nexpose']['install_args']
Remove invalid LICENSE file.
Fix regressions to Linux recipe from refactor

We broke Linux installation by not referencing node['os'] correctly
and leaving '/' out of the path to indicate the root level.
Add service on Linux and cleanup recipes.

Added support for enabling the service from Chef.

Did a couple miscellaneous cleanups to the default and linux
recipes.
Add checksum attributes for installers.

Add checksum attribute for installers. We typically update installers
on a weekly basis, however we have internal work in progress to deploy
a sha256 checksum file which we can download and parse to reduce the
overhead of redownloading them unnecessarily.
Merge pull request #6 from rapid7-cookbooks/feature/windows

Add Windows support.