integer_range validator for ELB HealthyCheckInt

Created an integer_range validator that allows us to construct integer
validators that require that the integers be in a specified range.

Used this on the ELB HealthyCheckInterval parameter to avoid letting
someone set it to 1 and then having the deploy fail.
Need assertRaises on every call
Merge pull request #7 from cloudtools/bvz-elb-healthcheck-min

integer_range validator for ELB HealthyCheckInt