vector: defaults and indexes

Added an pre-defined integer vector declaration. This makes integer vectors
easier to declare and pass around. Also, added the ability to default a vector
up to a given size with a default value. Lastly, added functionality that
returns the "nth" index of a matching value.

Also, updated a unit test to test these changes.

Change-Id: Iaf4b51b2540eda57cb43f67aa59cf1d96cdbcaa5