Make suggester implementation pluggable

This patch tries to make the suggester implementation as pluggable as
facets or highlight implementations. The goal is to be able to create
own suggest implementations in a suggest query.

Closes #3089
Making deb installable by being lintian compatible

According to #2515 the ubuntu software center does not allow to install
debian packages which are not lintian compatible

I worked on the package and made it lintian compatible by doing

* Ignoring errors about arch dependent binaries as we will not split
  this package. The arch dependent libraries are used correctly.
* Added a copyright file pointing to the apache license in debian

Closes #2515
Closes #2320