Only save "*txt" files

For now the logs are written to a very polluted directory so we need to
only grab the .txt files. Later, when the logs are moved to their own
directory, we can return to grabbing the whole directory.
Change compression to bzip2
Add Rsyncer.clean() to remove the tmp directory
Use normpath on locations

Normpath removes double / and removes "../", things which tar has
problems with.
Only backup one level of folders

We use cd to change to the directory we want to tar and then tar it, so
that we only have one level of directories stored in the tarball.