New Exception types: ConnectionException

[dmikurube]

We have had two standard Exceptions: ConfigException and DataException. But, we see another type of "typical" exceptions: errors in connecting to the target.

Things are TBD. But an idea is:

• abstract ConnectionException
  • Parent of the following two classes
• TentativeConnectionException
  • Possible intermediate network issues. For example:
    • Unknown host
    • Connection time out
• PermanentConnectionException
  • Expected not to be recovered until a specific fixing action is taken. For example:
    • Permission denied