deb: Downgrade recommended dependencies and add to description

Motivation:

According to Debian documentation, recommended dependencies are strongly
suggested and for dependencies that would be uncommon not to install. The
dependencies we list here are optional and only used by specific scripts not
used on all nodes.

Modification:

Reduce the dependencies to suggested dependencies. Extended the description
with when those dependencies would be used (following best practice outlined in
the Debian policy manual).

Result:

 new debian package, version 2.0.
 size 72748094 bytes: control archive= 17697 bytes.
     207 bytes,     8 lines      conffiles
     769 bytes,    19 lines      control
   46163 bytes,   530 lines      md5sums
    2382 bytes,    66 lines   *  postinst             #!/bin/sh
     161 bytes,     7 lines   *  postrm               #!/bin/sh
      99 bytes,     7 lines   *  prerm                #!/bin/sh
 Package: dcache
 Version: 2.14.0~1434541384261-1
 Architecture: all
 Maintainer: The dCache team <support@dcache.org>
 Installed-Size: 84040
 Depends: ssh-client, adduser, ssl-cert
 Suggests: ruby, libxml2-utils | xsltproc, python-psycopg2
 Conflicts: dcache-server
 Section: misc
 Priority: extra
 Description: distributed mass storage system
  dCache is an efficient, modular and configurable mass storage
  management system. It provides a system for storing and retrieving
  huge amounts of data, distributed among a large number of heterogeneous server
  nodes, under a single virtual filesystem tree with a variety of standard
  access methods.
  .
  The GLUE info provider requires either xsltproc or libxml2-utils. The StAR
  accounting record provider requires python-psycopg2. The example HSM integration
  script requires ruby.

Target: trunk
Require-notes: no
Require-book: no
Fixes: #1641
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/8316/

packages/fhs/src/main/deb/control

@@ -8,12 +8,15 @@ Standards-Version: 3.9.0
 Package: @PackageName@
 Depends: ssh-client, adduser, ssl-cert
 Conflicts: dcache-server
-Recommends: libxml2-utils, python-psycopg2
 Architecture: all
-Suggests: ruby
+Suggests: ruby, libxml2-utils | xsltproc, python-psycopg2
 Description: distributed mass storage system
  dCache is an efficient, modular and configurable mass storage
  management system. It provides a system for storing and retrieving
- huge amounts of data, distributed among a large number of heterogenous server
+ huge amounts of data, distributed among a large number of heterogeneous server
  nodes, under a single virtual filesystem tree with a variety of standard
- access methods.
+ access methods.
+ .
+ The GLUE info provider requires either xsltproc or libxml2-utils. The StAR
+ accounting record provider requires python-psycopg2. The example HSM integration
+ script requires ruby.