It's not appropriate to put binaries in /; binaries installed external
to the package manager should be installed in /usr/local/bin or
/usr/local/libexec on most systems. Since it's not meant to be executed
by users directly, it's probably more appropriate to be in libexec;
also, since "keyfetch" is a rather generic name, it's probably better to
rename it as "tangled-keyfetch".

Signed-off-by: Runxi Yu <me@runxiyu.org>

- implemented in a backwards compatible way, introduces migrations and
updates an existing lexicon
- newly added field is not marked required, so we should still be able
to index old repo-create events properly

This should help alleviate the memory leakyness that was exhibited when
we stored the entire object.Commit in memory.

no cap

We're open to public!

we want to enable proper rollback mechanism on knots to eventually

add git as a dep to knotserver

and trims timeline to 50 events now

do we bother with migrations yet?

nearly there; some hardcoded paths need tweaking for push to work

fix issue closing, indicate alpha etc