Removes the dependence with aptitude

Removes the dependence with aptitude by replacing
the call of:
  aptitude purge -y ~npackage by apt_get purge -y package*

Change-Id: I08875ffad9dc6293047827666f02453a355b16ea
Closes-Bug: 1281410
diff --git a/lib/databases/postgresql b/lib/databases/postgresql
index c459feb..96a5947 100644
--- a/lib/databases/postgresql
+++ b/lib/databases/postgresql
@@ -21,7 +21,7 @@
     stop_service postgresql
     if is_ubuntu; then
         # Get ruthless with mysql
-        sudo aptitude purge -y  ~npostgresql
+        apt_get purge -y postgresql*
         return
     elif is_fedora; then
         uninstall_package postgresql-server