Fix pip installation path

Added options for pip to ensure that python packages are installed into
the correct location. The specific option is install_args and without
this the Graphite related packages are installed outside the virtualenv
and can not be found when trying to start the services. By default the
Pip packages are installed in /opt/graphite. Refer to
https://graphite.readthedocs.org/en/latest/install-source.html for more
information.

By using install_args we can pass install options to pip and correctly
install the Python package to root_dir
Use root_dir in initdb_cmd variable
Ensure grpahite webapp dir is created

With correct permissions
Set path for exec resource 'set_graphite_ownership'
Fixing root_dir when installing with pip
Removing dot typo
Fixing lint issues (ignoring 80 characters)
Ignoring 80 characters lint check in a rake task
Make 'before' array more readable

As suggested in PR gds-operations/puppet-graphite/pull/31, made the
array used in 'before' more readable.
Use class param for user home

Set the users home to $::grpahite::root_dir
gunicorn_bin logic in class not template

Moving the logic out of the template and putting it in the class file,
should hopefully make it clearer about what is actually happening.
Fix initdb command

Incorrect path was being used for manage.py when pip is used. Also fully
qualify path to Python when Pip is not being used.
Remove ownership of config files

The graphite user will no longer own the the configuration files but can
still read, allowing the services to start.