Fix issues found by mass usenet dragnet.
Convert the read_file shim in the MIME tree from being synchronous to asynchronous.
Port the xpcshell glue code to use readFile instead of readFileSync.
Update mocha to 1.18.2, mostly to get new Promises support added in 1.18.0.
Fix up the Mocha tests to use the new return-a-Promise feature. The xpcshell glue changes are currently untested.
Simplify maybe-returns-a-promise handling of Mocha in xpcshell glue.
Revert bad commit.
Simplify mocha promise handling.
Merge with updated master.