Both boolean values are accepted for 'autostart' in template

In the template, there was an incorrect check for 'autostart'
parameter. Since it was boolean, 'false' value could never
be inserted in the configuration. This commit fixes it by
checking against :undef.
Allowing NONE logging; Checking for undefined boolean variables

Supervisord allows special values NONE and AUTO for the stdout
and stderr log paths. These should not be prefixed with the
path of the logging directory, which is ensured by this commit.

All boolean values in supervisord::program are also checked
against null, rather than false. Therefore, the user is able
to specifically add 'false' value to the config.
Stderr and stdout paths fix

There was a mistake of mixing up the stdout and stderr
paths. It is fixed now.
Merge branch 'master' of https://github.com/pavelsmolka/puppet-supervisord into pavelsmolka-master
Merge branch 'pavelsmolka-master'
added logging change from PR #27 to all define types
fixed linting issue