Fix logging in interactive mode

[amitbeka]

Fix some thorny problems with interactive mode logging in rdflib:

• When importing rdflib from the command line, it opens the loggers for every possible package, which is a very bad practice
• More over, when using jupyter console and importing anything that imports rdflib somewhere along the chain, all loggers in the system pour their logs. This is because the condition (not hasattr(__main__, '__file__') and sys.stderr.isatty()) is True but it's of course what we want here
• Another small fix is checking the stderr is a TTY, not stdout which isn't used

[gromgull]

this looks good! the travis build timed out, I've restarted it.

[joernhees]

thanks :)