Thunderbird 3.0b3 schedule change

[Dan Mosedale]

[cross-posted; replies to mozilla.dev.apps.thunderbird, please]

I spent a bunch of time talking to devs about the various remaining b3
blockers on Friday, and it became clear to me that there are enough
blockers that aren't going to make it by Tuesday that we really care
about (both in the Gloda search area and elsewhere), that we're going to
have to slip both the slushy string freeze and beta3 by some number of
weeks.

It doesn't seem obvious to me by how many weeks we want to adjust the
schedule; I'll be talking to drivers over the next several days and
expect to have a proposal soon...

Dan