View dependencies & a bunch of random unit test fixes

Allows specifying view dependencies like

```xml
<view name="view_one" dependsOnViews="another_view, other_schema.third_view" ...>
  ...
</view>
```

Diffing and building now respects view dependencies, and always issues `CREATE` and `DROP` DDL for depended-upon views first.

Additionally, fixes a bunch of global-scope/sequence test failures that were cropping up in Travis