Dockerfile: Symlink ruby2.0 to /usr/bin/ruby
Dockerfile: Symlink ruby2.0 to /usr/bin/ruby

brew tests fails otherwise.

1) Failure:
LanguageModuleRequirementTests#test_good_ruby_deps
[/home/linuxbrew/.linuxbrew/Library/Homebrew/test/test_language_module_requirement.rb:51]:
Expected #<LanguageModuleRequirement: "languagemodule" [:ruby, "date", nil]>
to be satisfied?.

Linuxbrew/brew,rwhogg/brew,Linuxbrew/brew,Linuxbrew/brew,Linuxbrew/brew,hanxue/linuxbrew,maxim-belkin/brew,rwhogg/brew,maxim-belkin/brew,rwhogg/brew,hanxue/linuxbrew,hanxue/linuxbrew,maxim-belkin/brew