change travis config to only upload escripts for tags (stable releases)

Cosmetic change: remove last comma-first style

This commit moves the handling of distribution config and starting out
of rebar_prv_shell and into rebar_dist_utils. The module is able to
handle standard config options and boot a distributed node mode. This
could be used in plugins (once it is exposed) and other providers like
CT.

Configuration is also expanded so that options like:

    {dist, [{sname, atom()}, {name, atom()}, {setcookie, term()}]}

can be used and will be handled as a default. The config handler
supports similar terms from the command line being parsed in if the
calling provider supports them.

A test suite is added for configuration handling.

rebranding: update links rebar/rebar3 -> erlang/rebar3

Fix Travis build status image in readme

Support all deps & locks in rebar3 path

Allow 'rebar3 pkgs <app>' to return only that app

Fix bugs/race conditions in shell

Unsure if this should be a final supported format or if we should
support other ways to match instead.

This is a demo to solve the issue hilighted in
https://github.com/erlang/rebar3/pull/1072

By default, the dependency only handled versioned packages and top-level
source dependencies, and locks were being ignored.

This patch makes it so locks and package deps are being considered,
generating full-blown path lists.

Should fix #1117

Following suggestions from @psyeugenic, this code terminates and waits
for the termination of the port handling IO before booting our own,
which should get rid of annoying warnings.

We also allow for the failure to shutdown the user worker under
kernel_sup, since it is likely not there anymore in many scenarios,
preventing crashes.

Allows overwrite the default cache directory using the environment
variable REBAR_CACHE_DIR.

pass loglevel used in rebar3 to relx

make omar happy

add definition of 'COMMON_TEST' macro to eunit provider

This reverts commit 4c32c52b55.

upgrade cth_readable

define the 'EUNIT' macro in the test profile

move dialyze setting of debug_info to overrides in profile

bump certifi to 0.4.0

latest mozilla bundles

include project_plugins in plugins that can be upgraded

Take CT options errors and turn them to warnings

The idea is that given we accept arbitrary config items for CT, we
should similarly be able to pass unsupported options and keep things
running.

However for unsupported options, a warning is very useful to have.

Fix quoting problem in zsh completion

add support for common tests `include` flag

error on a cover spec in ct_opts

Add short-options to the eunit provider.