[finishes #81400128] feat (koast) report koast version in header

- for use with [80580556] - having koast-angular know if versions match
- created middleware called version-reporter
- replace x-powered-by header with 'Koast' instead of 'Express'
- adds x-koast-version header that reports version from package.json
Merge pull request #72 from e-schultz/feat-report-version-in-headers

[finishes #81400128] feat (koast) report koast version in header