Update installation instruction for Debian

In the instructions on how to install Ganeti on Debian, have
the commands for Wheezy as default and mention the commands for
Squeeze as other versions, rather than defaulting to Squeeze.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>

INSTALL

@@ -57,21 +57,22 @@ Debian/Ubuntu, you can use this command line to install all required
 packages, except for RBD, DRBD and Xen::
 
   $ apt-get install lvm2 ssh bridge-utils iproute iputils-arping make \
-                    ndisc6 python python-pyopenssl openssl \
+                    ndisc6 python python-openssl openssl \
                     python-pyparsing python-simplejson python-bitarray \
                     python-pyinotify python-pycurl python-ipaddr socat fping
 
-If bitarray is missing it can be installed from easy-install::
-
-  $ easy_install bitarray
-
-Or on newer distributions (eg. Debian Wheezy) the above becomes::
+For older distributions (eg. Debian  Squeeze) the package names are
+different.::
 
   $ apt-get install lvm2 ssh bridge-utils iproute iputils-arping make \
-                    ndisc6 python python-openssl openssl \
+                    ndisc6 python python-pyopenssl openssl \
                     python-pyparsing python-simplejson python-bitarray \
                     python-pyinotify python-pycurl python-ipaddr socat fping
 
+If bitarray is missing it can be installed from easy-install::
+
+  $ easy_install bitarray
+
 Note that this does not install optional packages::
 
   $ apt-get install python-paramiko python-affinity qemu-img
@@ -148,16 +149,16 @@ deploy Ganeti on production machines). More specifically:
 
 Some of these are also available as package in Debian/Ubuntu::
 
-  $ apt-get install ghc6 libghc6-json-dev libghc6-network-dev \
-                    libghc6-parallel-dev libghc6-deepseq-dev \
-                    libghc6-curl-dev
-
-Or in newer versions of these distributions (using GHC 7.x)::
-
   $ apt-get install ghc libghc-json-dev libghc-network-dev \
                     libghc-parallel-dev libghc-deepseq-dev \
                     libghc-utf8-string-dev libghc-curl-dev
 
+Or in older versions of these distributions (using GHC 6.x)::
+
+  $ apt-get install ghc6 libghc6-json-dev libghc6-network-dev \
+                    libghc6-parallel-dev libghc6-deepseq-dev \
+                    libghc6-curl-dev
+
 In Fedora, some of them are available via packages as well::
 
   $ yum install ghc ghc-json-devel ghc-network-devel \