GitLab

* Add IAsyncApplication and AsyncApplication with RunAsync methods
* Extract IApplication interface from Application
* Move ArgsInput.Bind method to IInput interface
* Simplify Application.Run implementation

* NuGet deployments are only done for tagged builds now
* Fix unnecessary using statement

* Release v0.2.0-alpha2

* Values of IInput.Options may now be any objects
* Implemented multiple value options in ArgsInput

* Fixed wrong DefaultPushSource

* Fixed dotnet nuget push lacking a push source

* Added `deploy` stage, pushing the current master build to NuGet

* Added `dotnet clean` to build step

* Fixed nupkg path in pack job

* Removed unnecessary quotes
* Added stages to job configurations

* Added initial GitLab CI pipeline

* Fixed missing binding for default IInput in Application
* Added license file
* Added readme file

Features
* Simple Application class as the entry point into a terminal application
* Abstract Command class that can be extend and configure itself to accept arguments/options
* Arguments/options framework in order to define and validate command line arguments and options