warn if v2_key exists with meaningful error

fix_auth (the most common place to generate a key) tries to provide
a user context that they should not just remove the file.

The cli is more powerful, so a --force-key option is provided

- cli only replaces v2_key if --force-key
- cli does replace v2_key if fetching from remote
- fix_auth displays warning. User must backup key first
- cli displays warning. offers --force-key option
- change raise so the stack trace points to our code

https://bugzilla.redhat.com/show_bug.cgi?id=1153777
Merge pull request #936 from kbrock/protect_key

warn if v2_key exists with meaningful error
remove error text in lib rspecs

- fix stderr message from generating a v2_key when file exists
- removed rspec deprecation warning

DEPRECATION: any_number_of_times is deprecated. Use stub instead. Called from /Users/kbrock/src/manageiq/lib/spec/openstack/openstack_handle/handle_spec.rb:52:in `block (3 levels) in <top (required)>'.
Merge pull request #940 from kbrock/lib_spec_messages

remove error text in lib rspecs