Add AMD detection.
Add AMD detection.

Added AMD module loading to `rfc822.js`. Somehow, the module got
smaller.

    File                             Raw         Min         Zip     Min/Zip
    rfc822.js                 8196/08.00  3170/03.10  3461/03.38  1587/01.55

Closes #56.

bigeasy/timezone,bigeasy/timezone,bigeasy/timezone