Use a shared library to migrate your Visual Studio Tools for Office add-in to an Office web add-in

VSTO Shared code migration(#59)

* initial commit

* draft readme and start completed folders

* readme and minor updates

* changing folder name

* added solution setup steps

* incorporated review feedback

* added security notes and minor fixes

* remove unnecessary scripts

* added jquery cdn

* removed unneeded function

* renaming Office add-in project

* Update README.md

* update link

* update sample list

* reorganize sample list

* simplify descriptions

* simplify descriptions

* fix header