Add [sg]etter methods for optimizer params
Add documentation for class and [sg]etters
Remove `virtual` keyword from [sg]etters

These setters and getters are general enough that they shouldn't need to be
overridden by any subclass
Set defaults for optimizer params
Add defaults to documentation
Refactor GslOptimizer to use getters for params
Make optimizer parameters protected so subclasses can use directly
Pass GslOptimizer as the context to the GSL level

This is done so we can access parameters of the optimizer from the non-memnber
functions GSL needs.
Merge pull request #269 from dmcdougall/minimizer-options

Implement [sg]etter methods for optimizer parameters
Added rng method for getting a pointer to the gsl_rng object
Merge pull request #271 from eRite/fix_RngGsl

Added rng method for getting a pointer to the gsl_rng object
Make minimize method void and take no start point
Add logic for setting m_initialPoint to optimize
Add logic to error out on a bad initial point
Add logic for getting minimizer

Also do sane initialization of minimizer to GSL_NAN, and fix const correctness
of setting initial point
Update test to use new optimizer api
Merge pull request #272 from dmcdougall/refactor-minimizer

Refactor minimizer
Added enum for GSL optimizer solver types.

Also added setter and defaulted to BFGS2.
Added setter
Helper function

To determine if GSL optimizer needs a gradient