Upgrade to Elixir 0.11.2

Signed-off-by: chatgris <jboyer@af83.com>
Add _build to .gitignore

Signed-off-by: chatgris <jboyer@af83.com>
Upgrade deps

Signed-off-by: chatgris <jboyer@af83.com>
Add erlang-uuid

Signed-off-by: chatgris <jboyer@af83.com>
Add `/ohai` endpoint

Signed-off-by: chatgris <jboyer@af83.com>