Revert "Refactor SVN and cURL download strategies."

[ilovezfs]

Reverts #2848

[JCount]

@reitermarkus This had to be reverted because it was making bottle uploads to Bintray fail with:

Error: unknown keyword: extra_args
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Homebrew/utils/curl.rb:11:in `curl_args'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1265:in `block (2 levels) in test_ci_upload'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1256:in `each'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1256:in `block in test_ci_upload'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1250:in `each'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1250:in `test_ci_upload'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1429:in `test_bot'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Taps/homebrew/homebrew-test-bot/cmd/brew-test-bot.rb:1528:in `<top (required)>'
/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Homebrew/utils.rb:20:in `require?'
/var/lib/jenkins/workspace/Homebrew Bottles/Library/Homebrew/brew.rb:101:in `<main>'
Build step 'Execute shell' marked build as failure
[WS-CLEANUP] Deleting project workspace...[WS-CLEANUP] done
Finished: FAILURE

https://jenkins.brew.sh/job/Homebrew%20Bottles/7906/console
https://jenkins.brew.sh/job/Homebrew%20Bottles/7909/console
https://jenkins.brew.sh/job/Homebrew%20Bottles/7911/console
https://jenkins.brew.sh/job/Homebrew%20Bottles/7912/console
https://jenkins.brew.sh/job/Homebrew%20Bottles/7913/console

[reitermarkus]

Well, of course there had to be something that broke. 😭