Don't run dialyzer on R14 and below

Its too slow and the build fails on travis
Merge pull request #48 from ericbmerritt/next

Don't run dialyzer on R14 and below
Merge pull request #50 from tsloughter/master

remove dialyzer and test from all since we run travis on PRs
fixes #29 - look for common sub dirs for discovery

With this change relcool looks for the common sub directories to add
to the search. Those directories are now, relative to the project dir,
`apps`, `lib`, `ebin`, and the release output dir.

These automatic subdirs can be disabled by setting
`disable_project_subdirs` to `true` in the config.

The release output dir is also added to the discovery process. This
can be disabled by setting `disable_discover_release_output` to true.
set erlware_commons to come from master in rebar config
Update contributing document to new branch layout
Merge pull request #51 from ericbmerritt/next

various bugfixes to the system
make sure that top level releases are also supported

Add matching test
Merge pull request #52 from ericbmerritt/next

make sure that top level releases are also supported
Remove bin/erl before replacing it

In some erlang distributions (e.g. brew) the ERTS files do not have 
write permissions set.  When this is the case the file:write_file will
fail with error 'eacces'.

This commit removes 'bin/erl' before attempting to write the new file.
Merge pull request #53 from zerotao/master

Remove bin/erl from the local ERTS copy before writing a the new version.
add skip_apps config option to list discovered apps to skip