Set default debian install_opts to accommodate upgrades.

Without setting this, the cookbook as-is wont accommodate upgrades.
Default behavior of dpkg is to prompt when new package files will
clobber existing package files which have seen changes.  While apt
can have a global setting tuned to reflect similar install options,
this just assumes that you want to get to the declared version no
matter what state you might be in previously.
Merge pull request #8 from filler/add_debian_install_opts

Set default debian install_opts to accommodate upgrades.
Allow for connection pool filter to be more attribute driven.

The Solum project needs the encoding to not be chunked when proxying
to the origin server.  This change allows that to be tunable, along
with other attributes.