Created a new "octo pack" command.

Introduces `octo pack` for generating _.nupkg_ files without NuGet.exe or NuSpecs.

```
octo.exe pack --id=MyPackage
```

Will pack the current directory into a .NUPKG written to the current directory, with a generated version number

```
octo.exe pack --id=MyPackage --version=1.2.3 --author=nick --author=henrik --description="Awesome package" --releaseNotesFile=rn.xml --basePath=dist --outFolder=some/publish --include=**/*.js --include=*.html
```

Complete options:

```
Usage: Octo pack [<options>]

Where [<options>] is any of:

      --id=VALUE             The ID of the package; e.g. MyCompany.MyApp
      --overwrite            [Optional] Allow an existing package file of the
                               same ID/version to be overwritten
      --include=VALUE        [Optional, Multiple] Add a file pattern to
                               include, relative to the base path e.g. /bin/-
                               *.dll - if none are specified, defaults to **
      --basePath=VALUE       [Optional] The root folder containing files and
                               folders to pack; defaults to '.'
      --outFolder=VALUE      [Optional] The folder into which the generated
                               NUPKG file will be written; defaults to '.'
      --version=VALUE        [Optional] The version of the package; must be a
                               valid SemVer; defaults to a timestamp-based
                               version
      --author=VALUE         [Optional, Multiple] Add an author to the
                               package metadata; defaults to the current user
      --title=VALUE          [Optional] The title of the package
      --description=VALUE    [Optional] A description of the package;
                               defaults to a generic description
      --releaseNotes=VALUE   [Optional] Release notes for this version of the
                               package
      --releaseNotesFile=VALUE
                             [Optional] A file containing release notes for
                               this version of the package
```