Upgrade to Meteor 0.6.6.3 (security fixes).

* Updated installation instructions in the README; the "download binary
from curl" install is actually much more convenient, since it follows
the correct version of meteor automatically.

Meteor release notes:
https://www.meteor.com/blog/2013/10/10/meteor-066-content-security-policy-upsert-and-near-node-010
https://github.com/meteor/meteor/blob/release/0.6.6.3/History.md

Change-Id: I9577619adb1bdc09c39400739f753df1c589364f
Upgrade to Meteor 0.7.0.1 (scalability; performance fixes).

Meteor release notes:
https://www.meteor.com/blog/2013/12/17/meteor-070-scalable-database-queries-using-mongodb-oplog-instead-of-poll-and-diff
https://github.com/meteor/meteor/blob/release/0.7.0.1/History.md

Change-Id: I0a6c93ddb0653c11b21149707fceac030d56af1b