Correct Errors in Update rendering

Update was rendering a set of parenthesis around SET assignments

Fix Update rendering

Update was using a db wildcard for the table and that is not supported.

Return `chain.ErrNoRows` when `chain.ExpressionChain.Raw` yields no results

v0.1.4

Add exception for No rows returned from db

Correct `ExpresionChain.Raw` behavior

Raw was silently ignoring malformed queries and trying to execute empty ones (which led to unexpected behavior).
This was corrected and a test was added.

Null helper support

v0.1.2

Added Null and NotNull helpers

Vendoring of dependencies

Fresh out version with all dependencies (all 3) vendored.

Initial release

Initial release of gaum in a usable way.