Remove justMyCode default values in debug configuration

[dbaeumer]

#94

See screen cast. I can't step into the tempfile library.

[dbaeumer]

My failure. There was a just my code property in the launch.json :-(

[dbaeumer]

IM we should not generate the property in the launch.json since true is the default anyways. This allows to override the default via the setting and gives final control in the launch.json