Add user property for parameter "dataFile" of "report" mojo

[Godin]

See https://groups.google.com/d/msg/jacoco/XtIKmcuqbo8/LUJIIPLjvLYJ

[Tunaki]

This issue was referenced in the Stack Overflow question How to configure JaCoCo maven plugin from command line.

[widgetpl]

+1
but for me would be nice to have user property for all configuration parameters of JaCoCo plugin stages as it would alllow to run them from command line.

[luanzhu]

+1
This option is going to be very useful when the jacoco tcp server cannot be accessed directly from the mvn plug-in.

[Godin]

@widgetpl this is not that easy in case of properties whose values are not primitive, e.g. rules of check mojo, or even lists such as includes and excludes of report mojo, while it is easy in case of dataFile of report mojo. So instead of trying to climb a mountain using too general statement "all of them", let's do a baby steps and solve various cases separately, and especially that as of today there is not that much parameters, which cannot be specified from command-line.

[widgetpl]

@Godin yes You are right, I am requiring too much and for me dataFile is enough for now as i had problem just with this parameter and when i wrote about rest of them i thought that it might be useful in future for someone ;)

[Godin]

@widgetpl thank you for your understanding!

[Godin]

@marchof could you please review?

Funny that fix is one line, while changes for integration test much bigger 😄