Refactor repository layout and convert build system to Mage.

This commit implements a massive refactor of the repository, and
moves the build system over to use Mage (magefile.org) which should
allow seamless building across multiple platforms.

vendor/github.com/magefile/mage/README.md

@@ -0,0 +1,61 @@
+<p align="center"><img src="https://user-images.githubusercontent.com/3185864/32058716-5ee9b512-ba38-11e7-978a-287eb2a62743.png"/></p>
+
+## About [![Build Status](https://travis-ci.org/magefile/mage.svg?branch=master)](https://travis-ci.org/magefile/mage)
+
+Mage is a make/rake-like build tool using Go.  You write plain-old go functions,
+and Mage automatically uses them as Makefile-like runnable targets.
+
+## Installation
+
+Mage has no dependencies outside the Go standard library, and builds with Go 1.7
+and above (possibly even lower versions, but they're not regularly tested). 
+
+Install mage by running 
+
+```
+go get -u -d github.com/magefile/mage
+cd $GOPATH/src/github.com/magefile/mage
+go run bootstrap.go
+```
+
+This will download the code into your GOPATH, and then run the bootstrap script
+to build mage with version infomation embedded in it.  A normal `go get`
+(without -d) will build the binary correctly, but no version info will be
+embedded.  If you've done this, no worries, just go to
+$GOPATH/src/github.com/magefile/mage and run `mage install` or `go run
+bootstrap.go` and a new binary will be created with the correct version
+information.
+
+The mage binary will be created in your $GOPATH/bin directory.
+
+You may also install a binary release from our
+[releases](https://github.com/magefile/mage/releases) page. 
+
+## Demo
+
+[![Mage Demo](https://img.youtube.com/vi/GOqbD0lF-iA/maxresdefault.jpg)](https://www.youtube.com/watch?v=GOqbD0lF-iA)
+
+## Discussion
+
+Join the `#mage` channel on [gophers slack](https://gophers.slack.com/messages/general/) for discussion of usage, development, etc.
+
+# Documentation
+
+see [magefile.org](https://magefile.org) for full docs
+
+see [godoc.org/github.com/magefile/mage/mage](https://godoc.org/github.com/magefile/mage/mage) for how to use mage as a library.
+
+# Why?
+
+Makefiles are hard to read and hard to write.  Mostly because makefiles are essentially fancy bash scripts with significant white space and additional make-related syntax.
+
+Mage lets you have multiple magefiles, name your magefiles whatever you
+want, and they're easy to customize for multiple operating systems.  Mage has no
+dependencies (aside from go) and runs just fine on all major operating systems, whereas make generally uses bash which is not well supported on Windows.
+Go is superior to bash for any non-trivial task involving branching, looping, anything that's not just straight line execution of commands.  And if your project is written in Go, why introduce another
+language as idiosyncratic as bash?  Why not use the language your contributors
+are already comfortable with?
+
+# TODO
+
+* File conversion tasks