[MJAVADOC-664] - Fix stale javadoc data detection on Windows.

[Syquel]

Replaces the usage of the full commandline by only its arguments to generate the stale javadoc detection key.
This approach allows to handle file-arguments appropriately in case of double-quoting by resolving them to their actual arguments.

• I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

[michaelboyles]

Not a committer, but I think this unlikely to be accepted without a test

[slachiewicz]

How I can test that functionality?

[Syquel]

@slachiewicz I documented that mostly in MJAVADOC-664.
Do you need anything else?

Writing a unit test for this fix would require some time, which I am currently not able to invest, because there is no unit test for the feature itself yet.

//EDIT
For reference: #33 introduced this feature.