Arcyd: profile each 'git' and 'conduit' method

Fix the double-reporting of some conduit time and give more detail on
git time by reporting time spent in each of the object's methods
individually.

conduit.call directly uses conduit._communicate, so this time was being
reported twice in the 'conduit' sum.

Test Plan:
$ ./precommit.sh

Watched results in
$ ./testbed/arcyd/loop_test.sh