every time

Removing all the private constants.
The last constant VERSION_21 was accidentally added with a wrong value.
This shows that all these constants only make it easier to make
mistakes. It makes more sense to treat version as a number rather than a
sequence of magic constants.

Change-Id: I1f7e5cb19e28274f25cd65a6e28aaddf6c6137b6
Signed-off-by: Mateusz Matela <mateusz.matela@gmail.com>