Make default gateway IP '.1' instead of '.254' (#175)

* Make default gateway IP '.1' instead of '.254'

* Use .1 for default gateway instead of .254

* Updates to documentation:
Update documentation to use new year
Update documentation links to current working links
Update documentation to use Mandiant instead of FireEye

* Fix filepath of HTML report template

* Minor code cleanup

* Update CHANGELOG

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Co-authored-by: Tina Johnson <[email protected]>