Bug 1005413: Import JSMime from revision 8626a9039d66570124a9d1d7e54683d50f0f6570, r=irving.

Individual JSMime patches were reviewed by both irving and asuth.

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extra : rebase_source : a0338d3c7a3bb990a1352579ecdd1ffd38d69bd6
Bug 998189: Add a basic structured header interface, r=irving, sr=Neil. a=jcranmer

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extra : rebase_source : c021d947ba9760fa1004d72036493408604afc45