THRIFT-4904: Fix python unit test errors and exception escapes

Due to the way SSL layers on top of sockets, it was possible
to complete a connection and then have the server close it.
This would happen if the client is not checking certificates
but the server is.  The TSSLSocket unit test was enhanced to
do a read and a write as well as just connecting to ensure a
more complete test.

The TSocket read() and write() calls were leaking OSError,
socker.error, and ssl.Error exceptions.  These cases are now
wrapped into a TTransportException of the appropriate type,
and the original exception is added as an argument named inner.
4 files changed