Catkin should send out only one notification

[cbandera]

I have noticed, that catkin sends out several notifications after a build instead of sending one summary.

This leads to a poor user experience, as you might miss some information or even get a wrong idea about the success of you build as in this example:
Build a workspace with packages that produce warnings. After the build, you will get two notifications:

• "Build Suceeded. 5 packages completed with no warnings"
  
• "Build Produced Warnings. 1 packages succeeded with warnings"
  

This is especially confusing on system, where notifications don't stack, but really show up one after another, so that at first glance you only see half of the information.

I have therefor merged all information that is produced by the print_compact_summary function into a single call to notify, passing over all information at once.

[jbohren]

This definitely looks like an improvement. Now, of course, I want there to be a yellow/orange icon when there are warnings!

[jbohren]

@cbandera Our pedantic CI rig just needs the following to be fixed, then this should be good to merge after one of us tries it out.

../home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/controllers.py:367:81: E231 missing whitespace after ','
/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/controllers.py:376:31: E231 missing whitespace after ','
/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/controllers.py:389:87: E231 missing whitespace after ','

[jbohren]

c512b03 Awesome!

[wjwwood]

Thanks, this is great!