Update ChangeLog and version files for 0.7.3

ChangeLog

+2014-10-21, v0.7.3
+	* Instruct kamaki to ignore the ssl certificates (kamaki >= 0.13rc5).
+
 2014-10-14, v0.7.2
 	* Fix an exception triggered when collecting Ubuntu metadata
 

image_creator/version.py

 
-__version__ = "0.7.2"
+__version__ = "0.7.3"
 __version_vcs_info__ = {
-    'branch': 'hotfix-0.7.2',
-    'revid': '7b0713f',
-    'revno': 582}
+    'branch': 'hotfix-0.7.3',
+    'revid': '5de748e',
+    'revno': 586}
 __version_user_email__ = "skalkoto@grnet.gr"
 __version_user_name__ = "Nikos Skalkotos"