Ensure search request time bounds are respected

[cdbethune]

In the TA3TA2 API SearchRequest there are two fields set to specify time bounds:

    // Desired upper limit of time for solution search, expressed in minutes.
    // Default value of 0 (and any negative number) signifies no time bound.
    // See also time_bound_run.
    double time_bound_search = 3;

    // Desire upper limit of time for one pass of the pipeline run expressed in minutes.
    // Expressed at time of search, TA2's should limit the search to solutions
    // that would not take longer than this for one pass of the pipeline run.
    // Default value of 0 (and any negative number) signifies no time bound.
    // This can also functionally be used as the time bound for scoring also.
    double time_bound_run = 9;

We should have some support now for the first limit although it needs to be tested. What we can do for the second is not clear, but worth investigating.