The library is used in glanceclient/common/https.py and the
documentation build for the API fails without the dependency.
Update the error handling so that when OpenSSL reports an error it is
converted to a client communication error.
Change-Id: I0c0fb3139bb848d0cbaf88ae6a767a730bea74eb
Signed-off-by: Doug Hellmann <doug@doughellmann.com>