Expand parameter checks to Shepherd-interpreted params, closes #54

Hello @nicks, 

Please review the following commits I made in branch 'kylehardgrave-complete-param-checking'.

c5d3c662c18086591109678ff3a576289a58952c (2013-06-18 15:24:35 -0700)
Expand parameter checks to Shepherd-interpreted params, closes #54
Add tests for said checks


R=@nicks