always exec the concatfragments script as root when running as root

This is to allow the concatfragments script to be installed into a path that may not be accessible by a non-root user.
remove usage of resource defaults for file owner/permissions

In addition, the permissions of the fragment directory and files is now fixed and not world readable.
remove dead files
rename README.markdown -> README.md

For better consistency with other PuppetLabs' modules
fix or suppress all lint warnings
allow concat::fragment target param to be an arbitrary string

Revert validation of the target param as an absolute path and allow it to be an
arbitrary string.  This is so the

    concat { <foo>: path => ...  }
    concat::fragment { ...: target => <foo> }

association may be symbolic as long as concat path param is specified.  This
should resolve the symbolic name regression introduced in:
https://github.com/puppetlabs/puppetlabs-concat/commit/eaf84079
Merge pull request #94 from jhoblitt/symbolic_names

allow concat::fragment target param to be an arbitrary string
Merge pull request #93 from jhoblitt/tidyups

Tidyups
Merge pull request #91 from jhoblitt/exec_as_root_when_root

always exec the concatfragments script as root when running as root
deprecate concat::fragment mode, owner, & group params

There's no need to allow the ownership/permissions of a fragment to be set as
the concat define sets ownership/permissions on the final aggregated file.
Merge pull request #95 from jhoblitt/fragment_params

deprecate concat::fragment mode, owner, & group params