EC2 Inventory Boto Profile Support

This PR effectively combines #5987 and #8582. It also fixes the merge conflicts in the two PRs and standardizes the option names.

There is a minor inconsistency right now with the cache directoy names. If you use the AWS_PROFILE environment variable, your cache directory name will not change. However, if you use the CLI option or the config option, the cache directory will be named after the profile. We could check the AWS_PROFILE for naming, but the behavior is debatable and should be discussed on the ansible-devel mailing list.