Add versioning and schema migration for master catalog

[senderista]

We need to allow upgrading existing Myria clusters in-place, including when the catalog schema has changed. This would require adding a version field to the catalog (probably in a singleton table), and adding code accompanying any schema change to upgrade the catalog schema from the previous schema version. I don't think we should support upgrading from versions older than the immediate predecessor.

This should fix issues like #841. @dhutchis @jingjingwang @jortiz16 please comment.

[dhutchis]

In case it's helpful, this is the command I executed in SQLite to upgrade

ALTER TABLE relation_schema ADD is_indexed INTEGER NOT NULL DEFAULT 0;
ALTER TABLE relation_schema ADD is_ascending_index INTEGER DEFAULT 0;