Improve error handling

[1dustindavis]

This PR improves error handling of panics by recovering from any expected panics, printing the error, and then calling os.Exit(1).

Current situations where we expect a panic:

• Unable to write log file
• Unable to download a catalog
• Unable to parse a catalog
• Unable to download a manifest
• Unable to parse a manifest

My current thinking is that these are all situations that, if we continued past the error, may cause undesired or unknown effects, so our best option is to exit.

This would resolve #65 and #57. It would also contribute towards #15.

This PR also adjusts the arguments passed to choco so that it will output more details and we will catch those in our logs, which should address #58.

[1dustindavis]

Here are examples of the output when the download fails(404)

Normal Output (not verbose):

> gorilla
Unable to retrieve manifest: employee.yaml : Download status code: 404

Verbose Output

> gorilla -v
Retrieving manifest: employee
Manifest Url: https://example.com/gorilla/manifests/employee.yaml
Unable to retrieve manifest: employee.yaml : Download status code: 404

[1dustindavis]

While testing, I found a bad bug that the a previous PR created. We were only using item.Uninstaller.Location, not item.Installer.Location, so all installs failed 😑.

The latest commit to this PR fixes that issue, but I don't want to merge this until new tests are written to validate the URL.