Keep backtrace in order, and try to show the application_trace frame if it exists, related to rails/rails#17312
Fix binding change after security patch

The security patch introduced a regression with the binding change from
the UI.
Merge pull request #63 from gsamokovarov/security-regression

Fix binding change after security patch
Introduce basic Rubinius support

This one didn't see the testing it deserved and can be implemented
better by using Rubinius internals, rather then this shaky
`binding_of_caller` frame guessing. For now, I wanna roll this out as a
experimental Rubinius support. We'll make it better post `2.0`.

I'm seeing gem installation errors on Travis at the moment. Both for
Rubinius and JRuby. I really wanna get them off the allowed failures, so
I'm gonna keep an eye out in the upcoming days.
Merge pull request #64 from gsamokovarov/rubinius

Introduce basic Rubinius support
Merge pull request #60 from bronzle/fix_exception_app_to_show_user_code_frame

Keep backtrace in order, and try to show the application_trace frame if ...
Format console errors similarly to IRB

Currently, if an exception is raised during input console input sending
it will look like:

```
>> raise
!! RuntimeError
```

Now, we can show a backtrace in a similar format to IRB. It will be
cleaned up of the framework traces until the REPL for noiseless
debugging.

```
>> request.missing
NoMethodError: undefined method `missing' for #<ActionDispatch::Request:0x007fb6228197e8>
	from /web-console/test/dummy/app/controllers/exception_test_controller.rb:13:in `test_method'
```
Merge pull request #66 from gsamokovarov/dummy-repl-adapter

Format console errors similarly to IRB
Render console only from whitelisted IPs

This one wasn't implemented during this year GSoC. However, we can't go
live without it.
Merge pull request #67 from gsamokovarov/guard-non-whitelisted-ips

Render console only from whitelisted IPs
Update version to '2.0.0.beta4' in README

[skip ci]
Merge pull request #68 from jonatack/patch-1

Update gem version to '2.0.0.beta4' in README
Fix exception page console regression

The regression happened after #67.
Merge pull request #73 from gsamokovarov/fix-exception-page-regression

Fix exception page console regression
:burn: terminal at /console

For the sake of the users, let's not include this in 2.0. It may seem
messy from project history perspective, but let's not put this burden to
the users in 2.0. Closes #70.
Merge pull request #74 from gsamokovarov/kill-terminal-for-good

:burn: terminal at /console
Align the implementation with upstream Rails

This is getting really hard to maintain as is.
We no longer need the vendors

Leftover for #70.
Merge pull request #76 from gsamokovarov/clean-vendors

We no longer need the vendors
Merge pull request #75 from gsamokovarov/align-with-upstream-implementation

Align the implementation with upstream Rails