Consider contributing a few examples to etsdemo.

[rahulporuri]

For the 5.0.0 release, it might be good to contribute a few of the example envisage applications to the etsdemo application. The following examples work as expected and make for a good start :

• hello world.
• MOTD.
• tasks attractors.

[kitchoi]

Some of these examples assume a specific Python Path when they are run.
Some of them have side-effect of creating a log file in the current directory where they are run.
I am not sure etsdemo is mature enough to handle all these... it might need a bit more investigation to scope.

[rahulporuri]

I think it's perfectly understadable to update/modify the existing envisage examples to suit the way etsdemo works.

[kitchoi]

Actually I think it is probably better to change the examples such that it can be run from anywhere: It makes etsdemo optional, and anyone can run the examples even without the demo application.

We should get rid of the side-effect of logging to a file: it is quite annoying to run an example and realize it has left behind a file.

[kitchoi]

After #377, #379, we are left with these actions (I think):

• Remove logging to a file side-effect in examples. They are not particularly useful and is unexpected.
• Move the examples into envisage, update the single URL in docs/conf.py, make sure the files are distributed as package data, and add an entry point.