Added stdout and stderr output capturing, user config loading and simplified the repl tests.

Firstly, the web console now displays stdout and stderr correctly created from commands. For example the following all work as expected now:

    .ls
    puts "hello"


I also added support for loading from the user's config files (ie `~/.pryrc`), and to use custom printers (eg with [awesome_print](https://github.com/michaeldv/awesome_print)).

Finally, I simplified the tests, and added a few of my own testing my new features.