Updated README.

Also some minor cleanup.
Merge pull request #10 from blakejohnson/levenberg-docs

docs: Updated to reflect new `levenberg_maquardt()` method
Added proper show() and repl_show()
Revised simulated_annealing() to maintain a trace object

Cleaned up namespace handling
Started an automatic test suite
Cleaned up Nelder-Mead code
Revised Newton's method
Updated naive gradient descent code
Updated L-BFGS code
Revised optimize() interface
Updated grid_search() test
Updated BFGS and cleaned up tests
Move finite differencing into the Calculus package
Using the new OptimizationState() method.

Also adds LM to the run_tests script.
Merge pull request #11 from blakejohnson/levenberg-optimState

Use the new OptimizationState() method in levenberg_marquardt()
Updated to new Calculus API
Update to latest Julia file operations
Update to the latest Julia ops
Update for Julia deprecations (push!, delete!, and numel)
Change alphamax to reduce roundoff problems
Add nonnegative least squares