Fix "overlapping domain" Dialyzer warning for '#is_record-'/{1,2}

These contracts will usually not be seen by the user, and are ignored
by Dialyzer because they have overlapping domains, so there is not
much point in using them.  Replace with simpler contracts for now.
Merge pull request #7 from legoscia/is_record_overlapping_contracts

Fix "overlapping domain" Dialyzer warning for '#is_record-'/{1,2}
Fix compilation (dependency wasn't fetched)
Update rebar

The main purpose of this update is to make it work with
erlang.mk and other non-rebar build tools. Rebar now
supports a REBAR_DEPS_DIR environment variable making
this possible.
Merge pull request #8 from essen/fix-compile

Fix compile
redefine source of deps.