Losing internet connection makes the application hang

[mtbannister]

If the connection is lost, validate.py hangs with the log (below):

Interestingly, the 'Readings' window still responds to tabbing, but the image does not change.

Exception in thread Thread-2:
Traceback (most recent call last):
File "/Applications/Canopy.app/appdata/canopy-1.0.0.1160.macosx-x86_64/Canopy.app/Contents/lib/python2.7/threading.py", line 551, in bootstrap_inner
self.run()
File "/Users/michele/Dropbox/ossos-pipeline/src/ossos-pipeline/ossos/gui/downloads.py", line 74, in run
downloaded_image = self.downloader.download(reading)
File "/Users/michele/Dropbox/ossos-pipeline/src/ossos-pipeline/ossos/gui/downloads.py", line 195, in download
apcor_str = self._download_apcor_file(apcor_uri)
File "/Users/michele/Dropbox/ossos-pipeline/src/ossos-pipeline/ossos/gui/downloads.py", line 173, in _download_apcor_file
vofile = self.vosclient.open(uri, view="data")
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 1227, in open
URL = self.getNodeURL(uri, method=method, view=view, limit=limit, nextURI=nextURI, cutout=cutout)
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 993, in getNodeURL
return self._get(uri)
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 1104, in _get
return self.transfer(uri, "pullFromVoSpace")
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 1125, in transfer
con = VOFile(transURL, self.conn, method="GET", followRedirect=True)
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 616, in __init
self.open(URL, method)
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 689, in open
self.httpCon = self.connector.getConnection(URL)
File "/Users/michele/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/vos/vos.py", line 131, in getConnection
raise ex
IOError: [Errno 61] _ssl.c:489: The handshake operation timed out: 'www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca'

[ijiraq]

@drusk .. please solve by catching the Errno 61 [ECONNREFUSED] and popping up a re-try dialogue. This is different from getting an Errno13 [EACCES] which might indicate that the person certificate has expired and so then the pop-up should ask if the user would like to pull a new certificate.