Improvements

Thanks again for sharing this nifty little package, we rely heavily on it for your web tests. :)

I made the following enhancements.
* If build of web project fails: Exception message contains build errors.
* "Clean" target is executed before "Package" target to avoid that old versions of the web project are deployed.
* Web projects can now be deployed to a custom application path.

Currently we are using our own build of the project, but we would appreciate if you could update the NuGet package.