Delete dpkg call to avoid breakage on RPM-based systems

This commit gets rid of the unless condition in the call to install Ceph.
Running "ceph-deploy install" on a host where Ceph already is installed
doesn't cost a lot, but by having a hard-coded dpkg call in here, we're
in fact breaking compatibility with Red Hat and CentOS systems for no
real reason.
Fix handling of the file name of zapped status files

This commit changes the way that puppet-cephdeploy keeps track of which
disks have already been zapped. Previously, puppet-cephdeploy would
simply create a file for every device it has successfully zapped, and
that file would be inside of the "zap" directory of the ceph deploy
users home directory. Typically, device names are specified using a
"/dev/sda"-like syntax though, so infact, the modules would just try
to create $HOME/zap/dev/$NAME for every zapped disk. Because the name
may contain an arbitrary number of directories, this is a problem as
we can impossibly create matching subdirectories for every path that
may occur.

With this commit in place, the zap files will be created based on the
actual device ID, i.e. the last part of the device's specified path.
Configure the appropriate package repos on Debian/Ubuntu/RHEL/SLES

This commit adds functionality to puppet-cephdeploy to automatically
install the required repositories into the system configuration. The
inktank repositories are required to install ceph-deploy and the rest
of Ceph, so puppet-cephdeploy should be able to handle them. The
repos will automatically be deployed on hosts that have "cephdeploy"
assigned to them as a class.

The "ceph" and "ceph-extra" repositories will be added.

Currently, RHEL- and compatible systems as well as SLES 11 and the
Debian OS family (so Debian and Ubuntu) are supported.