Update dictionary option for follow apport spec with apport.report.Re…

…port.search_bug_patterns(). See http://bazaar.launchpad.net/~apport-hackers/apport/trunk/view/head:/doc/crashdb-conf.txt

bug_pattern_base option is deprecated some years ago and replaced by bug_pattern_url.
The old configuration is harmless because use a None value, but it is better update with the new config key
for avoid future problems.

(bzr r55.16.1)

debian/unity-crashdb.conf

@@ -1,5 +1,5 @@
 unity = {
  'impl' : 'launchpad',
  'project' : 'unity',
- 'bug_pattern_base' : None,
+ 'bug_pattern_url' : None,
  }