Support for versioning artifacts produced by project

[farrukhnajmi]

At present the project does not appear to define a version for the artifacts produced by the project. For example, in current pre-release state it would be good to version the project as 1.0-SNAPSHOT.

I will be working on this issue in my fork at https://github.com/farrukhnajmi/ExtendedCalendarView

Given that most new projects are now using gradle for build I am inclined to used gradle in my proposed commit for this issue in my own branch. Project contributors(s) please let me know if you have any suggestions or input. Thanks.