Add client-config-dir name parameter with optional inclusion in template

Add ccd variable defaulting to 'ccd' and updated the server.conf template
to conditionally add the client-config-dir line if ccd is not empty.
Parameterize more variables to improve flexibility and add a few

Added tls_verify which defaults to nothing
Added custom_options to add additional options not handled by parameters
Moved verb & status-log values to be parameters
Updated server.conf template to allow for variables to be removed
Corrected option name typo in server.conf

Config erroneous had log_append added rather than the correct option log-append
which generates a runtime error when attempting to start OpenVPN.
Merge pull request #4 from jbouse/master

Add additional flexibility to openvpn server configurataion