New rule: Disallow mixes of different bitwise operators

[feross]

Proposal to make the no-mixed-operators stricter so it includes bitwise operators.

This was suggested by @mafintosh in this comment: #566 (comment)

[mafintosh]

tbc, my issue is when mixing bitwise ops with +, *, === etc. mixing them with other bitwise ops is pretty straightforward

[feross]

@mafintosh Yep, got it. The rule won't warn about operators that are equal precedence. Parens are only needed when mixing operators of different precedences.