[activesync] Support delayed body fetching (no snippet support yet)

Fix snippet length stuff (who cares what the commit message is, I'm just going to rebase aaaaaaaaaaaaaaaaaaaaaaa)
Fix behavior with old ActiveSync versions (cargo-culting my old example code!)
Update test server
[activesync] Add deferred body support for ActiveSync 2.5
Incrementally call put/delete in db
remove parallel snippet fetching in favor of parallel body fetching
Add option for specifying maximum bytes to download in FE
Address review comments
address asuth review
[activesync] Add support for do_downloadBodies
Factor out common body updating code
[activesync] When downloading bodies for snippetizing, prefer a short plain text snippet if the full body is too big
Merge pull request #182 from mozsquib/as-body-fetch

Bug 861859 - Implement lazy body fetching for ActiveSync