package compliance with debian distribution

Hi,

I'm issuing this pull request as I tried to build the package for my debian distro (with a dedicated repo) but I can with few problems... I'm hoping that my work will be pulled so it makes people life easier as well.

Summary:
* error in version number if packages/debian/changelog: -0 isn't a valid release number (changed to -1)
* missing the init script for debian as debian doesn't use upstart, so created one based on bind9 and integrated my modifications
* added compatibility with resolvconf so the dns server created by dnscrypt-proxy can be added to /etc/resolv.conf
* updated the upstart script not to fail with resolvconf variable
* fixed a lintian warning regard packages/debian/control in the Description field.
* moved --user=dnsccrypt to /etc/default/dnscrypt-proxy so the end user has the ability to override this at will or discard the feature altogether (though not recommended).

Note:
* The package is 100% compatible with debian and lintian doesn't display any error or warning once the package is created.
* the folder ./packages/debian should be in ./debian instead for an easier use

Cheers