Fix frozen string literal issues part 2

[chaadow]

Followup: https://github.com/fog/fog-aws/pull/709

After running tests locally I managed to fix all of the frozen string literals issues.

This PR however depends on fog-core and fog-xml being fixed ( I will create separate PRs on those repos) EDIT: here are the 2 PRs:

• https://github.com/fog/fog-core/pull/300
• https://github.com/fog/fog-xml/pull/27

It's worth mentioning that on fog-core and fog-xml, I will just fix just enough to make the tests green here I haven't yet run the tests on those repos.

@geemus What do you think? Do you mind providing me with a simple github action .yml file in which i can enable RUBYOPT

here is the command I run locally: bundle exec rake RUBYOPT="--enable-frozen-string-literal"