Allow application update on non released versions

2014-12-10 18:05:28,532 2484 2272 INFO     nxdrive.controller Fetched update info from server: {u'serverVersion': u'6.0', u'updateSiteURL': u'http://community.nuxeo.com/static/drive-tests/'}
2014-12-10 18:05:28,576 2484 2272 INFO     nxdrive.controller Proxy settings successfully updated: ProxySettings<config=System, proxy_type=http, server=, port=, authenticated=False, username=, exceptions=>
2014-12-10 18:05:28,657 2484 2272 INFO     nxdrive.controller Fetched update info from server: {u'serverVersion': u'6.0', u'updateSiteURL': u'http://community.nuxeo.com/static/drive-tests/'}
2014-12-10 18:05:28,661 2484 2272 DEBUG    nxdrive.updater    Application is frozen, building Esky instance from executable C:\Program Files (x86)\Nuxeo\Drive\appdata\nuxeo-drive-1.3.1210.win32\ndrivew.exe and version finder http://community.nuxeo.com/static/drive-tests/
2014-12-10 18:05:28,717 2484 2272 DEBUG    nxdrive.updater    Fetched client minimum version for server version 6.0 from http://community.nuxeo.com/static/drive-tests/6.0.json: 1.3.1107
2014-12-10 18:05:28,815 2484 2272 DEBUG    nxdrive.updater    Fetched server minimum version for client version 1.3.1107 from http://community.nuxeo.com/static/drive-tests/1.3.1107.json: 5.6
2014-12-10 18:05:28,861 2484 2272 ERROR    nxdrive.updater    HTTP Error 404: Not Found
Traceback (most recent call last):
  File "nuxeo-drive-client\nxdrive\updater.py", line 238, in get_server_min_version
  File "C:\Users\nuxeo\AppData\Roaming\Python\Python27\site-packages\esky\finder.py", line 165, in open_url
  File "C:\Python27\lib\urllib2.py", line 127, in urlopen
    
  File "C:\Python27\lib\urllib2.py", line 410, in open
    def _open(self, req, data=None):
  File "C:\Python27\lib\urllib2.py", line 523, in http_response
    https_response = http_response
  File "C:\Python27\lib\urllib2.py", line 448, in error
    # make sense to include both
  File "C:\Python27\lib\urllib2.py", line 382, in _call_chain
    def open(self, fullurl, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
  File "C:\Python27\lib\urllib2.py", line 531, in http_error_default
    # this is needed because of the state that cookies introduce
HTTPError: HTTP Error 404: Not Found
2014-12-10 18:05:28,868 2484 2272 WARNING  nxdrive.updater    Missing or invalid file '1.3.1210.json' in update site 'http://community.nuxeo.com/static/drive-tests/', can't get server minimum version for client version 1.3.1210
2014-12-10 18:05:28,871 2484 2272 WARNING  nxdrive.gui.application Some information or version file is missing in the update site, as a consequence update features won't be available