Test results more measure funcs

[ian-sift]

Per-customer desire, this PR creates 3 new functions for recording test resuts:

• measure_avg: Calculate the average of a list of values, measure the average against given bounds, and return the result.
• measure_all: Ensure that all values in a list are within bounds and return the result. Records measurements for all values outside the bounds
• report_outcome: A generic catchall: Report an outcome from some action or measurement. Creates a substep that is pass/fail with the optional reason as the description.