mention all and none as version schemes

[tschmidtb51]

I suggest to add the version schemes all and none that are defined as follows:

all

There is just one possible form: vers:all/*. It matches all versions. A comparison whether a version is within the range always results true.

Use case: E.g. an affected EOL product that will never be fixed.

none

There is just one possible form: vers:none/*. It matches no version. A comparison whether a version is within the range always results in false.

Use case: Sometimes people as a negated question - e.g. 'Which versions are affected?' Answer: None.

Flagging @pombredanne for attention