MB-8239  Fixed cbcollect_info for OSX.

Setting COUCHBASE_TOP env variable here so that erl shell
script can find erlang install path.

Change-Id: Id666f0658351b7767993a5cad66c10eee12cd6b4
Reviewed-on: http://review.couchbase.org/26511
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>