Issue 2
This is a tar-command that will, via PEAR/archive_tar, create a tar-file.
I've, essentially,based this on ISSUE-3 and the work of Christian in that branch.
One note: I'm not super thrilled about the tests, for two reasons.
ONE: I do not test when there is an error
TWO: I'd like to run the test with a mock of the file system and since the paths that the tar-files should be placed, comes from another object/service, I haven't managed to figure that out yet.
So this means that my tests now compress an actual php-file and an actual tar-file is created. I find this abit scary.