v0.021

    Write new Primer3 config values into parameters file.
    Throw a more meaningful error when Primer3 dies.
    Can set Primer3 gc_clamp value.
delete old cmd
add gibson deletion design commands
change default offsets for gibson deletion designs
update farm wrapper script
wip, make parse failed design attempts script work for deletion gibson designs, need to re-work script in future to make it more flexible
use cmd_options hash to fill in the design_parameters data for a design attempt, stops the design_parameters data in the design attempts table being only partially there
pass the options hash to the create_design_attempt_record subroutine
fix tests, the offset values for gibson deletion are now 1 both five prime and three prime, used to be 200 bases 5 prime and 100 bases 3 prime
throw a more detailed error if we fail to find any valid primer pairs for a one or more regions
code tidy
add tests for validate_oligo_pairs subroutine, uncomment tests
add tests for output_valid_oligo_pairs subroutine in FilterGibsonOligos role
    Store all command parameters when creating initial design attempt record.
    Throw custom error class when we do not have any valid primer pairs for a region.
    Change default offsets in gibson deletion designs.