Repo clean up

[kejacobson]

Changes towards cleaning up some of the existing code:

1. Class names are converted to CamelCase to meet PEP-8 conventions
2. The tacs object is renamed from tacs to tacs_assembler to avoid name conflict with the tacs module being imported.
3. To address issue Remove "mphys_" prefix from files, classes, and methods. #30, several mphys_ prefixes have being removed from file names and class names. Files that will move to other repositories still have the prefix as well as mphys specific methods added to OpenMDAO groups/components.

[kejacobson]

Needs to be tested on the examples before merging

[joanibal]

Thanks Kevin!

The only inconsistency that I could find was in the capitalization of VLM in DummyVLMSolver. It seems like it should be DummyVlmSolver to match VlmGroup and VlmBuilder

[kejacobson]

Thanks for reviewing it Josh. I've made the dummy VLM solver name consistent.

[anilyil]

thanks for the work @kejacobson I have pushed 2 commits:

First one also updates the name of the SolverGroup the way you updated other mphys groups.

The second commit is related to typo fixes in adflow wrapper. I realized I enabled the propulsion "hooks" in adflow on by default, I disabled this by default and it is now activated via an input parameter to the builder. I know other builders may not have input parameters to the builder but I wanted to have these custom for adflow; default behavior is same across other builders, and I can specialize it for my cases. If we want to create a default mphys api for this type of stuff, I can modify the adflow wrapper again.

After my changes, all examples under mach_tutorials folder works as expected. If you also approve my changes in the last 2 commits, I think this PR is ready to be merged.