Add Parameter Validation

[jinlow]

Right now there are a lot of parameters that have required ranges that are not being validated. There is some validation defined by the constraints of the types (usize can't be negative for instance), but this should all be handled in one place.
Create a InvalidInputParameter error, and then inside of GradientBooster::new check for valid parameters returning an error if some criteria are not met.

[gravesee]

This looks helpful: https://crates.io/crates/validator

[jinlow]

Checked out this package, pretty cool! After some testing, it ended up being easier to just write a small function to validate the float params. Additionally, reading through this issue it has some thorns/maintenance concerns. The nice thing is, most of the parameters are self validating by their actual data types, so the only validation that currently needs to happen is to make sure some floats are positive.

[jinlow]

Merged, and released