Simplest implementation of a `blacklisted_keys_pattern` option

Prevents the Rails exception handler from sending translations when their key is blacklisted.
Blacklisted keys also apply to options[:scope]
Update README and CHANGELOG
Merge branch 'master' into exception_sending_blacklist

Conflicts:
	CHANGELOG.md
Merge pull request #155 from Locale/exception_sending_blacklist

Create a blacklist pattern that filters out keys that shouldn't be automatically sent to Locale servers