v1.0.0 - dotnet global tool

With this version the dotnet-version-climoves away from a cli tool that is installed on a csproj file and becomes a standalone dotnet 2.1 global tool.
Thanks to @mikey0000 for the initial work on making this happen!

First upgrade your dotnet SDK to at least 2.1.301 and then install the tool by:

dotnet tool install -g dotnet-version-cli

Now you can use the tool everywhere on your machine with dotnet version.

Support for passing in the csproj file to work on has also been baked in:

dotnet version --project-file=./src/my.csproj minor

To bump the given csproj file with minor