Add support for 'safe' combinations filter

[bryandonmarc]

Feature request: Support for random names without obscene, NSFW, or otherwise sexually suggestive combinations.

Currently, the haikunator.haikunate() can result in inappropriate combinations such as

haikunator.haikunate();
// Sexual combinations:
// => throbbing-wood-6969 (or hard-wood, morning-wood, tiny-wood, etc.)
// => tight-queen-6969
// Drug-related:
// => green-bush-1420
// Religious taboos:
// => dark-voice-6666
// etc.

Reason: One of the combinations above actually appeared when a teacher was generating a random classroom access code while testing my learning management system project. It was downright embarrassing.

Work-around: I've modified the default list of nouns and adjectives and removed those which I think might result in inappropriate combinations. As for the random number token, I've placed a while condition which generates a new random token while the current token matches a list of inappropriate digit combinations e.g. 69, 420, 666, etc.