Make initial ./ optional when stripping ./.eunit/

On my system (Ubuntu 14.04.1), the filenames in .eunit were being
found without the initial ./. This caused the sed expression that trims 
off ./.eunit/ to not match,  and therefore leave the ./eunit. For example, 
when running unit tests on the quick start guide project, I would get the
following:

beam/beam-load.c(1250): Error loading module '.eunit/unit-my-test-lib-tests'

Presumably, the other sed commands that would strip ./.eunit/ off
would fail similarly, so the match for those has been updated too.