Extract reusable functions into webdevutils package

This removes some of the validation logic from the main package for
`staticserve` to a more reusable package that can be shared independently of
the packaged command-line tools.

Also added gocheck tests for webdevutils shared lib.
Initial cut of autocompile command
Add packaging and cross-compilation support

* Add fpm gem dependency
* Add cross-compilation for Linux packaging
* Add vagrant gem dependency from git
Add initial Travis CI support

* Add .travis.yml
* Remove cross-compile bash function dependency from Godeps
* Remove upx since it has issues on Linux amd64 where Travis runs
* Update README to include Travis CI status image