Merge pull request #91 from lcowell/encode-decode

add config.Encode/Decode
Make ToFile() a method on config
Make golint happy in config package
Simplify CI
Make encode a method on config
Use pointers to Config

We really don't need to pass copies of the entire object around.
Don't use named returns in config
Get rid of named returns in main
Remove go vet from travis build
Do not print to stdout from config package