add tests for ExplicitBundler
refactor to break large method into smaller ones
merge base and explicit bundler, no need for separation
Merge pull request #22 from mikey179/bundler-merge

merge the explicit and the base bundler into one class
add tests for construction of CompleteBundler
refactor: keep package dependency internal

As the bundler is created from a package anyway and there is alsways one bundler instance for each single package, it is not required to pass the bundler to the build method.
Merge pull request #23 from mikey179/package_internal_bundler

Let bundlers know about the package they are for