use 3.0 native format

3.0 (native) source format allows for using xz which
  compresses source to 3.4MB instead of 34MB
remove mongodb dependency

It is not a package dependency.
Mongodb could be running on a different server and is not a required
package for this package to function.
Include charmload

run tests.
Update readme

TARGETPPA is used differently now.
Merge pull request #4 from jrwren/master

remove mongodb package dependency