Sbt project structure

Hey @andre-nunes!
Let's bring some order in the project structure using sbt.
I guess, you've already seen this [guide](https://github.com/laughedelic/fake-wiki/wiki/working-with-sbt-projects). 

- [x] I see the `build.properties` file in the root — it should be in `project/` folder, as well as the `project/plugins.sbt` file. See the first two steps of the guide.
- [x] now, you have a lot of jars in the `lib/` folder. I guess, they are dependencies. In general you shouldn't use unmanaged dependencies. Instead, you can add references to them in the `build.sbt` and sbt will manage them automatically. It will look something like this (in `build.sbt`:

  ```scala
  libraryDependencies ++= Seq(
    "com.tinkerpop.blueprints" % "blueprints-core" % "2.5.0",
    ...
  )
  ``` 
  note that you should list only _direct_ (top-level) dependencies, as sbt will automatically resolve all their dependencies. After doing this, you should remove the `lib/` folder.
  See also the [official sbt docs on this](http://www.scala-sbt.org/0.13/tutorial/Library-Dependencies.html).
- [x] the `tools/` folder shouldn't be in the repository — it's not related to the code
- [x] the `src/` folder is fine :+1: 
- [x] please, create the `docs/` folder, to store there the code docs and any relevant project documentation
- [x] in the `build.sbt` file, add `bucketSuffix := "era7.com"` as it was written in the guide

- [x] And a little comment regarding one coding convention: the package name of the source file
  - should have a prefix `com.<org_name>.<project_name>` (like on github, this is `bio4j/exporter`)
  - should correspond to the folders structure starting from `src/main/java/`, i.e. if the file is `src/main/java/bio4j/exporter/foo/bar/Qux.java` than it's package should be `com.bio4j.exporter.foo.bar`


I think, it's enough for the beginning. I will write about more things later.
Try to fix these things, and if you have any questions, don't hesitate to ask, I'm glad to help you :wink: 

P.S. you can use the checkboxes in this post when you are finishing each step.