Automatically replace XLL version information with data read from an assembly

This is a (slightly modified) feature request that was asked in the mailing-list, so just adding as an issue so we can track this better and possibly encourage someone to implement and send a PR.

Original requests:
- [Exposing resource info in ExcelDNAPack](https://groups.google.com/forum/#!topic/exceldna/GusDyS0Sf0U)
- [Versioning the xll for Windows Installer](https://groups.google.com/forum/#!topic/exceldna/HlVeZUZNcqM)

My assumption is that the developer (or ideally the continuous integration system) should be responsible for setting the right version information about the add-in, in the main assembly (or in all of them). With that said, we should be able to describe in the Excel-DNA XML file which assembly should be used to read version information about the add-in (version number, copyright, product name, etc.) and any information available in this assembly should automatically replace what is in the XLL file, during the build of the project.

I would suggest this to be implemented as a regular MSBuild Task, rather than implementing this as part of the ExcelDnaPack utility given that people might not care about packing their add-ins - and still would like to get version information in the XLL that gets copied during the build.