This patch removes some of our freedom patches that have been deprecated
for some time now.
Some of them have been updated so we’re not shipping code based on an
old version of Rails.
When plugin spec is evaluated for the first time, it took 30 seconds to run:
```
rm -rf tmp/* && LOAD_PLUGINS=1 be rspec ./plugins/discourse-solved/spec/requests/topics_controller_spec.rb
```
Applying sprocket patch in test environment solves that issue
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Loïc Guitaut
Krzysztof Kotlarek
Sam Saffron
Guo Xiang Tan