Fix import paths in "make test" dependency fetching

When running "make test" on my machine, I got many unrecognized import
path errors, and the path showed a trailing "\n". Changing the go list
format to remove the newline fixed these.

builder/amazonebs: Default to AWS env vars for key and secret

[GH-92]

packer: Provide line number for invalid json syntax [GH-56]

[GH-91]

/cc @smerrill

Log Packer OS/Arch to Debug

Log Packer Version to Debug