Merge pull request #19 from ericbmerritt/next

overlay support
use relative root for overlay vars file path
fix bug in goalless configs
add tests to try and cover unexpected failures
minor format refactoring
provide the erlang lib dir and cwd as working libraries

This happens for every call unless the user passes
--disable-default-libs to relcool or {disable_default_libs, true} in
the relcool config.
make common_test support explicit

The rebar support for common test is very, very buggy and it fails
often without common_test failing due to how rebar integrates with
common test. This patch takes the responsability for running common
test from rebar and runs it directly.
change the default log level to info

This makes it a bit more comforting to the user (and me as well). With
this the user sees a short description of the release.
Merge pull request #20 from ericbmerritt/next

overlay directory support
fix and normalize module headers
convert relcool to take a config as a opt argument

adds `-c <config-file>` or `--config <config-file>` instead of passing
the config file as an argument.
fix a bug in running ct tests
Merge pull request #21 from ericbmerritt/next

working towards release upgrades
support the discover task searching the output dir

This has the potential to save a lot of time and make future release
upgrading much simpler for the user.
Merge pull request #22 from ericbmerritt/next

support the discover task searching the output dir
move app discovery to a dedicated module
fix bugs in constraint parsing for rcl_release
fix release processing bugs in rcl_prv_release
support release discovery in relcool along with app discovery
fix formatting bigs in depsolver