Debian packaging - first release

Hi,

As discussed on the forum, I've revised the debian installer so it can cope with leaving the Apache-served files in the root directory. This makes the "debianization" changes fully backwards compatible with all existing installations.

I've modified the readme and done a little other housekeeping too; you should be able to try this as a clean install following those instructions and it should work (as demonstrated by Paul).

I'll follow this up with pull requests on the modules - at least the easy ones - as the same process can be applied to them. If we can tackle that (and remove the PEAR/PECL dependencies) we'll have a really clean install procedure.

*important* - if you do merge this in, please add an annotated tag onto master: debian/8.0 (this is very important so we can track what's on apt as distinct to what's on git master).

I will then refresh the apt repository with a deb built against the emoncms:master (as opposed to my own fork of emoncms, which is what is currently there).

Thanks!