Make the namespacing used for --deb-changelog consistent with other
fields - fixes #543
deb-upstart: automatically symlink to upstart-job

When --deb-upstart is given, automatically create a symlink to
/var/lib/upstart-job for each given paramter.
Merge pull request #545 from igalic/upstart-symlink

deb-upstart: automatically symlink to upstart-job
- mkdir necessary directories
- style
- give a better error message if the user provides an invalid or
inaccessible path
- give a better error message if you specify a config file path that
doesn't exist.
symlinks... fucking symlinks.

get the symlink syntax right.
Merge pull request #546 from igalic/upstart-symlink

symlinks... fucking symlinks.
Merge pull request #544 from torrancew/fix_deb_changelog_path

Make the namespacing used for --deb-changelog consistent with other fields