Bug 1097421 - [email] Upgrade email.js omnibus bug. r=jrburke

Land https://github.com/mozilla-b2g/gaia-email-libs-and-more/pull/353
See its individual commit comments and the bugs dependent on bug 1097421
for more info.

Note that this also includes 2 autoconfig changes:

- 126.com: This makes us consistent with 163.com, another mail domain also
  operated by netease which also uses the coremail mail server and whose
  ActiveSync implementation does not work so well with our implementation.
  This avoids its autodiscover exposure capturing us and causing us to use
  its ActiveSync implementation.  This is basically required since the
  Mozilla ISPDB is not capable of overriding the ISP's entries.  (Which is
  desired in most cases for many reasons, but being able to say "don't use
  that ActiveSync implementation!" would be helpful.)

- yahoo.co.jp: Right now the ISPDB says to use POP3.  Only with these fixes
  do we work with yahoo.co.jp's IMAP implementation, so (selfishly), it's
  better to do this for now than to change the ISPDB.
Merge pull request #26566 from asutherland/upgrade-emailjs

Bug 1097421 - [email] Upgrade email.js omnibus bug. r=jrburke