Record version in evn: rev props during pre/post commit.

[tpn]

There is currently no way to determine whether or not Enversion hooks were enabled for a given revision, or if a revision was post-processed during the analysis stage.

Alter Enversion to record the following revision properties during pre/post-commit:

evn:pre-commit
evn:post-commit

is the version string returned from evnadmin version.