Add pe prefix to deb repo creation

For pe, the deb packages are staged under the pe directory, and the deb repo
creation task was hardcoded to use just deb. This commit conditionally adds a
pe prefix to pe builds. This really just makes the hard coding a little better,
and could probably be abstracted in a better way.
Merge pull request #127 from haus/add_pe_to_Deb_repo_creation

Add pe prefix to deb repo creation