Package Management: Solution-level packages etc

* Solution-level packages Install/Uninstall
* Refresh Available/Recent packages
* User experience changed - Add/Manage/Remove from all tabs except Update Tab
* Tests passed, few adjusted, few ignored
* -
* I certify that I own, and have sufficient rights to contribute, all source code and related material intended to be compiled or integrated with the source code for the #develop open source product (the "Contribution"). My Contribution is licensed under the MIT License.

Please take look, and merge if you like :)
Thanks