README: minor improvements

 - Add 3y3 to the list of maintainers.

 - Remove dependency status badge as it is reporting dependencies from
   npmjs.org instead of github master, which unnecessarily casts bad
   light on the project.

 - Remove broken link to "rc" github repo. It's enough to have a link
   to npmjs.org.
package: update dependencies, use "^"
test: fix race condition in launcher

Fix the code launching the debugged process and a debugger connection
to wait for "Debugger listening" message before opening the TCP
connection.
README: fix link pointing to docs.strongloop.com