WIP - Feature/mavenize project

This isn't quite right, yet. Bear with me and I'll get toopher-java mavenized.

I think it will be easiest to distribute the project if [we convert it to Maven](http://blog.sonatype.com/2009/04/how-to-convert-from-ant-to-maven-in-5-minutes/). It's doable with Ivy or Gradle, but it's simplest with Maven.

The `pom` file is a fairly simple port of [the Ivy file](https://github.com/toopher/toopher-java/pull/5).

I converted to Maven by creating a `pom.xml` and changing the project structure, then removed unnecessary files, reformatted the code and organized imports.

Here's the new project layout:

    ├── src
    │   ├── main
    │   │   ├── java
    │   │   │   └── com
    │   │   │       └── toopher
    │   │   │           ├── ApiResponseObject.java
    │   │   │           ├── AuthenticationStatus.java
    │   │   │           ├── PairingStatus.java
    │   │   │           ├── RequestError.java
    │   │   │           ├── ToopherAPI.java
    │   │   │           └── ToopherAPIDemo.java
    │   │   └── resources
    │   └── test
    │       └── java
    │           └── com
    │               └── toopher
    │                   └── TestToopherAPI.java